Dunno if it’s bad, but it can be ugly, and silver lip plates in particular can get major black marks and streaks on 'em. It looks dirty even if it isn’t. One good solution is a nice rubdown with quadruple-ought grade steel wool; very fine and kind to the silver; no scratches, just a nice clean-and-polish job comes of it. A repairperson told me that that was definitely one way to go, and I like it, as I’m leery about getting cleaning fluids on the wooden parts.
And definitely don’t lotion up your hands before you play. I played a school-owned bassoon in high school, and the girl who used it before me would do this a lot, and the keys always looked horrible.