Warning for the cripplingly self-conscious: a study from the University of Missouri has shown that crappy comments on your profile picture can negatively affect how attractive people find you not only in a physical sense, but in a social and professional one as well. At least in people who try to gauge attractiveness from nothing put a profile picture.
The study was done by paring the same pictures with different surrounding comments; bad comments made pictures score lower while good ones helped. According to Seoyeon Hong, one of the authors of the study, it all has to do with the fact that people are going to trust other people's perceptions of you (comments) more than the message you're trying to send (the picture), or even what they think when they see it. Even sarcastic comments or jokes can have an effect, so "Lol, u look so trashy loljkjk" could knock you down a peg, on top of betraying the fact that you socialize with idiots.
It's not just the comments though, action shots, or pictures that suggest you have interests and friends also tend to be rated as more attractive that solitary self-shots in the bathroom mirror, or even worse, your old yearbook picture. Of course, it's up to you to decide whether or not it's worth it to care and meticulously police your page, or take your picture in a lobster costume or something and let the haters hate. [MU News via Mashable]