There are plenty of things that drive me nuts about cosplay, but one situation in particular weirds me out...
My big cosplay fandom is Get Backers. The two main characters, respectively, wear dark pants/white dress shirt with long tails/round purple sunglasses, and khaki shorts/white t-shirt/green vest with a bunch of pockets.
This is not far from normal street clothes, so frequently I see people who are wearing dark pants/white dress shirt/sunglasses at a con and go "...Is that Ban?" because they don't have any of the telltale details that would make me know they were Ban. The shirt doesn't have long tails, the sunglasses are neither round nor purple, they haven't made even a half-hearted attempt at the hair... And of course, the same thing goes for Ginji as well - someone wears khaki shorts, a white t-shirt, and a vest of some color or another without the pockets, and I find myself wondering if they're supposed to be Ginji.
And it's not like it makes me MAD to see people doing this, because I'm not really sure if they actually are cosplaying or not (and far be it from me to tell people they can't do ghetto cosplay if they are - it can be fun). It might be a guy wearing dark pants, a white dress shirt, and sunglasses because that's how he dresses. It just really confuses me. -_-
"If people are going to laugh anyway, I want to try to make people laugh, and then laugh myself."
-Emishi Haruki, Get Backers