Um.
Well... there are still alot of racists, and people who root for someone just because they are of their own race/skin color.
BUT
I dont think its so much in bodybuilding, as in the rest of the community.
That being said, if Dennis Wolf were black, he would look much larger. On stage standing next to other bodybuilders, Wolfs true size comes out; but in the gym when hes by himself, his white skin tone really really diminishes how big he looks. Watch his videos, by himself he doesnt look nearly as big as some of the guys he dwarfs on stage do when they are by themselves.