Nothing drives me nuts more then people that try to pull off costumes inappropriate to their body types. No matter how good the costume is, it cannot hide the wrong body inside.
What's it going to take for them to admit that they should not be wearing that costume? A prime example is of this woman that I've seen going to major cons for the last couple of years, including this one. Her picture is everywhere! She's dressed as Power Girl. Yes, she's buxom enough but she's also too...well, how do I say it? FAT! There it is. Now it's not a secret. Now would somebody PLEASE go and TELL her?!