Source: Atlas Obscura
There are tired tropes that never actually happen in real life -- and there are also tired tropes that don't even happen in fiction. Ask anyone about these, and they'll tell you, "oh sure, this always happens" -- and yet they've never seen it themselves, or at least not an awful lot. These are the cryptids of fiction -- many believe in them because other people tell them they're real, but when it comes to finding them, you'll be lucky to come across a hair or a pile of poop. (OK, this metaphor stopped working at some point). What we're getting at is, these are way less common than many people think they are -- when they exist at all.
Source: Movies Silently