i voted both, but it is pretty harmless. there's always someone in the band that embarrasses the rest of the members. just be thankful your singer isn't embarrassing you--he'd be doing much worse things.
although i have to say that one bassist i played with was a huge michigan u fan. i showed up at the practice space to get my drums a few hours before a show, and he was there, wearing a michigan doo-rag, a michigan sweatshirt with the sleeves cut off, yellow sneakers, and.....oh, it pains me to remember this...michigan parachute pants.
the guitarist and i looked at each other, and i said to the dude, "you're not wearing that tonight are you?" he seemed a bit offended, and he did indeed take the stage in that costume.
and we were a metal band for pete's sake!!! how do you go out there and crank out pantera, fear factory, and sepultura songs looking like that???
i feel your pain.