i think it all has to do with self-confidence.  i've seen a lot of "ugly" people thinking they're the hottest things on earth, and some of the most "beautiful" people thinking that they're unattractive.  it only adds fuel to the fire, when enough people give compliments or just the opposite.  
take a look at hotornot.com.  i don't know if all the submitted pictures are of their own, but you can kind of get an idea.