8 Gadgets That Lie to You Every Day

The biggest reason for this is the float used to measure your gas level, which is a bulb on an arm like the one in your toilet tank. Bulbs are always going to be fatter than the arm, so you can go from full (float is completely submerged) to a little less full (float is floating on surface of gas but is touching the top of the tank) without the arm moving.

For the exact opposite reason, you can go from almost empty to empty without the arm moving.

So since your fuel needle is going to be in the same place for both full and slightly less full, the engineers chose to point it to full. The alternative is a fuel gauge that would never point to full and just confuses the driver. And since it's going to point to the same place for empty and almost empty, they chose to point it to empty.

On the other hand, think about how stupid you'd have to be to run out of gas if your fuel gauge was accurate down to the last drop, instead of forcing you into a guessing game once the fuel light came on. For something that everyone relies on at least once every month, it's weird that fuel gauges only actually convey information for the part of the gas tank when you need them the least, and are totally incapable of conveying information when you're on the verge of running out of gas on a desolate, serial killer laden wooded road. It may not cost you money, but not knowing the difference between 5 and zero percent means that you have to spend 5 percent more of your life standing at a pump.

It's one of those ideas that seems smart in theory when it's controlling the behavior of those other idiots who can't handle the truth. But when you're late for a meeting and don't know if you have 40 or zero miles left before empty, it's harder to swallow.

But at least it's a mechanical error. It's not like they're intentionally tricking us, like a dog owner pump faking a tennis ball, unlike ...

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Firefighters and other emergency personnel actually do need to speed things along sometimes, so the button does work for them if they use their key, but if you're not there to haul people out of a burning building, you are probably out of luck.

Crosswalk buttons are the same deal, at least at timed traffic lights like the ones in busy downtown areas. The light was going to change every two minutes anyway, and you pushing the button doesn't hurry it along any faster, although it does stop you from spazzing out about how long it's going to take. "I've given the order," you think. "Things are being seen to as we speak."

Good Morning America had a lot of time on their hands and actually checked out buttons in a number of cities, only finding one functional one. It's important to note that many traffic lights (especially in the suburbs) are sensor-driven instead of strictly timed, to the point where sometimes the light for the smaller side street actually never turns green unless something triggers it -- like a car, or a pedestrian pushing the button -- so obviously the buttons have to work there.

But apparently downtown districts are full of people pushing buttons that do nothing, and feeling very satisfied about it.

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It's more than just a Brit problem -- an American study of scales at the University of North Carolina found 20 percent of scales to be off. Only two other studies on U.S. scale accuracy have been done since 1981, so we could be overdosing patients left and right and not even know why.

Even when inaccurate scales aren't killing people, they are cheating people (or companies) of millions of dollars. In Maine, tons of people complain every year about being cheated by inaccurate firewood weighings, and while we do make a lot of baseless complaints in the U.S., inspectors found 90 percent of those complaints to be true.

If you want to go to Maine to see the firewood cheating in person for some reason, you'll pass through an airport and weigh your baggage on a scale, paying more if it's over a certain weight. Those scales are pretty questionable, too. Inspections found a surprising number of inaccurate scales at a variety of airports, including over one-third of the scales at Long Beach Airport and over half the US Airways scales in Phoenix.

Most of the scales were biased in favor of the passenger (underestimating baggage weight), so you might think it's no big deal since you don't get overcharged, but an overburdened plane running out of fuel in mid-flight could be equally inconvenient, depending on your priorities.

Luckily (?) it doesn't. Building facilities people know better than to trust us employees with those controls. One specialist estimates 90 percent of office thermostats do absolutely nothing. In an industry newsletter poll, 51 out of 70 respondents said they'd personally installed a fake thermostat.

And psychology is a beautiful thing. Apparently for most people, just turning a dial on a thermostat can make them physically warmer. One bank installed three fake thermostats, one for each complaining teller, and they were all completely satisfied with their "personal temperature controls."

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If the only thing you used a GPS device for was to tell you where you were, there would be no problem. Most GPS devices are accurate to within one meter, which is pretty amazing if you consider this is some machine in outer space telling you where you are.

Unfortunately, most of us use GPS systems to tell us where to go, which is where we start to put a lot more faith in them than we should. Programs aren't always smart enough to account for construction or scary cliff roads or other human elements. We've all heard stories about people who appear to lack all common sense, obeying a GPS order to turn right and driving down some railroad tracks, only to be surprised when they run into a train.

But it doesn't just affect the kind of clueless people that make for a rare wacky news story. According to one survey, 290,000 drivers in the U.K. reported getting into an accident or near-miss directly due to following their GPS. Tourists driving through California's Death Valley have gotten lost and even died, not due to the failure of the high-tech GPS tracking but due to the low-tech error of outdated maps being entered into that high-tech machine.

All the technology in the world can't do anything for you if the map it's given to read is wrong, and you can bet the map companies aren't sending people out to drive and check every single road they're feeding into the computer. So, especially in the cases of rural and less-traveled areas, there are a ton of nonexistent roads sitting in the computer, just waiting to be traveled by some poor sucker.

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The bad news is that your speedometer very likely is lying to you. But the good news is that it's probably erring on the side of caution -- if you're going 70 mph (which of course you wouldn't, because very few speed limits are above 65), the average speedometer would read 71.37. Worst case scenario, if you were driving on bald tires (2 percent), with your tire pressure off by 5 psi (1 percent), with the maximum error allowed by U.S. regulations (4 percent), in a Midwest winter (2 percent) and your alternator was acting up (1 percent), your speedometer could be off by 10 percent, or 7 mph if you were driving 70.

But again, there's no legal troubles with your speedometer being too fast. What you have to worry about is if the cop's speedometer reads high, since they often verify your speed by matching speed with you. Traffic cops tend to test their speedometers fairly often, but the standard across all auto manufacturers is that you can be up to 4 percent too high but cannot err on the low side. So if the cop's speedometer is off at all, it's off on the side of catching you.

But if the accuracy of your own speedometer is an issue (for setting personal records or something), one way to deal with that is to buy a cheap car. Apparently cars less than $20,000 have more accurate speedometers than luxury cars.

And if you don't want to switch cars but really care about knowing your own speed, well, ironically your GPS might actually be the better bet here.

That's why it's kind of disturbing that 30 to 40 percent of blood pressure cuffs are wrong by 4 mm Hg (pressure units) or more, and 10 percent are off by 10 mm Hg or more. The doctors in that article estimate that consistently high misreadings off by just 5 mm Hg would double the amount of patients being treated for high blood pressure, meaning some people would be gulping down pills they don't need, suffering side effects for no practical reason and paying for it to boot.

They can't just bias it one way like the speedometers either, because consistently low misreadings by 5 mm Hg would remove two-thirds of current high blood pressure patients from treatment and leave them in danger without realizing anything was wrong.

Also if you're fat, using a regular-sized cuff on you could overestimate your blood pressure by about 6 mm Hg.

So you'd be taking drugs you don't need and paying for them, and you'd be fat. Can't catch a break.

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Cellphones actually lie to you about two things -- battery life and bars. When it comes to battery life, phones often lie to you, like the government, for your own good.

The main issue is that most cellphone batteries are never kept at "100 percent" charge, because being at 100 percent charge can do long-term damage to the battery. Instead, phones are made to charge up to 100 percent, and then let the battery drain up to 10 percent, and it will "rest" in that state until you take it off the charger.

The phone will say 100 percent when you remove it from the charger, because if it didn't, you'd go, "I left this phone on the charger all night, why didn't it reach 100 percent yet?" and complain to customer service about the phone or the charger being broken. So it reads 100 percent at first to keep you happy, and then, in the interests of truth, the phone will quietly pretend the battery is draining over the next few minutes until it reaches 95 percent or whatever charge the phone is really at. It appeases both your expectation to see 100 percent when you take it off the charger, and your need to see an accurate battery reading as soon as possible.

The only side effect might be you getting annoyed that your phone "drains really fast" after you take it off the charger, but not a lot of people go to the returns desk for that.

The cellphone "bars" that indicate signal strength are also lying to you, in a number of ways. The simplest one is that in most cases, the bars have nothing to do with signal quality. PC World tested cellphone service in 13 cities and found that only one city (Phoenix) showed a correlation between bars and service quality. In San Francisco, only 13 percent of their test calls showed any relationship whatsoever between bars and quality.

There's two other keys to the puzzle that would really tell you what your service quality is. One is a number called EC/I0. The bars tell you how much signal you're getting, but the EC/I0 number tells you how much is actually usable. They don't put that on your phone because it changes so fast your bars would spaz out and never give a single solid reading, which would drive most users nuts and send them to the returns counter. The second key is that cellphone communication goes two ways. The bars tell you how well you're getting signal from the tower, but nothing can tell you how well the reverse link -- from your phone to the tower -- is working.

All the forward link (tower to phone) quality in the world won't do you any good if your reverse link is weak or down. And that's not something your phone can really tell you. But don't you worry your pretty little head about that, because here's some bars to keep you happy.

Not everything on your phone is sweet, sweet lies, though. Your Angry Birds score is probably accurate.

For humans who have deceived you over the years, check out 6 Lies About the Human Body You Learned in Kindergarten and 6 Famous Explorers Who Shaped The World (With Insane Lies).

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