C'mon, cosplay is something done for the purpose of having fun! Besides, you can always do something more low-key and appropriate. If you're 6'5", you shouldn't cosplay a small character. If you're ugly, you shouldn't cosplay a bishonen dude. And if you're a landwhale you shouldn't be cosplaying at all. Perception is the problem most of the time, but if you have the minimum of self-awareness, you can look in the mirror and say "Wow, I definitely look retarded" before doing a trainwreck. I for the life of me wouldn't try anything involving purple wigs or crazy bodypaint, but I don't see that as a reason to disregard cosplaying altogether.