Say what you will about the new Los Matadores gimmick WWE has been teasing for Primo and Epico, but it wouldn't be nearly as bad if they didn't have those masks. Look at those things.
They're ugly. They look cheap. And why are they pink? They'd be just fine in the matador outfits with traditional wrestling masks. Even Zorro-style masks would be better.
Awful costumes like that can kill a gimmick. In no particular order, and not counting anything intentionally bad (like Bastion Booger's outfit), let's look at some of the worst.