[mangoandmimi]

Don't know about acne but they would be prone to scratches etc or perhaps bruising which sounds more likely, could it be that? They cannot fit through tighter spaces like a furry hamster can as the skin gets caught so make sure all openings in the cage to houses etc are large enough to not catch.

Not sure about sand baths as those are used to clean the fur itself so not sure it would apply to a hairless ham.