I haven't noticed, probably since everyone I've worked with so far has had good hygiene. If a stunk-cock smelled funny or had an ashy dick I wouldn't work with him. Same thing if a girl smelled bad or was yeasty. No way would I share a toy with her or lick her pussy.

I also think BO smells like onions, no matter what the skin color... Just my opinion, and it's gross. Sometimes I can smell someone just by walking past them, or working out next to them at the gym. Color doesn't seem to make much difference in my experience. Stink is stink.