As I understand, fluffers are far less common than they once were. I think these days you really only see them on gangbang or orgy sets, while on more normal shoots, it's generally expected that the male performer will simply be ready to fuck. (Viagra, et al, have had a hand in this, I think, though those drugs have mainly expanded the talent pool for guys.
Though I'm no expert. Just what I've heard. :)