#1.) The extreme close-up.
Some women use a picture of just one eye, or just their lips. Guys seem less likely to use this one. But it sends a message that this one feature is the best you can do, and everything else will be downhill from there.
#2.) The three-quarter turn.
This one is more of a guy thing. You turn your face slightly away from the camera, like you want to show people your good side. But if you even know you HAVE a good side, you're probably a narcissistic D-bag.
#3.) The hot friend.
Some people use a picture of themselves with a really attractive friend. This is either to distract you from all the things about them that are NOT hot, or to brainwash you into thinking they ARE hot, just by association.
#4.) The no-show.
Sometimes you get that blank profile pic, or that default silhouette of a head that looks like a shooting range target. Or someone puts up a picture of their cat, or their baby, or an inspiring cliché of some kind. It's all probably about some personal crusade to convince the world that looks don't matter. Or worst of all, they might actually be obsessed with cats.
#5.) The intentionally ugly face.
Good-looking people do it to make you appreciate their beauty even more. Everybody else does it to make you laugh, because maybe they're just not that attractive.