Does it depend on the breed whether a cat is more or less cleany?
I'd say it depends on the individual cat's personality rather than on the breed.
I can't remember how much time my "regular" cat used to spend grooming but my hairless cats don't really sit and put time into grooming for some reason like most cats do, I hardly see them groom. I've heard that grooming is part of those very important social skills kittens learn and that it's very important for a cat to groom, not sure how accurate that is though. But I agree with Ruslana it might just be a personality thing,