Even the so-called "eyewitness" accounts of extraterrestrial landings we see on those History Channel UFO specials describe the aliens as being essentially human in appearance, with identifiable arms, legs, eyes, and heads. Hell, even the xenomorphs in the Alien franchise, which were supposed to be inhuman bug monsters, were so close to us they could be played by humans in costumes. The point is, that our idea of intelligent life is dependent upon the assumption that the human race is a common point of reference, despite the fact that in all likelihood this is crushingly incorrect.
But the greater question is, "If aliens aren't going to have boobs, do we even want to meet them?"
The truth is, we don't know the first goddamned thing about what the makeup of life is in the Quasar Nebula or whatever distant star cluster aliens might hail from. The dominant life form on their planet could be a fart cloud of neon gas and space lightning that communicates with a series of atonal whistles, by changing the temperature of the air around them, or even by emitting certain smells (though to be fair, some human beings communicate in this third fashion).
In other words, even the basics of life as we know it on Earth (I.e., that carbon is the base element) is by no means the fundamental rule of the universe. Carbon may not even freaking exist on the aliens' home world. The reason we have yet to make contact with alien civilizations may very well be because we wouldn't recognize them even if they sat down in the booth next to us at Applebee's.
"Sorry, we don't serve hyper-intelligent shades of blue. Store policy."