I'll never forget a few years ago when he was on Letterman. (I think it was just after his first solo album was released.) Can't remember what song he did, but he was in full rubber-horror dress, screamin' and sweatin' his head off. He was getting so worked up you could hear him start to lose his breath. The total image of evil, gory darkness.
After it was all over and Dave walked onto the stage, Rob let rip a super friendly "Hi Dave.." sounding like the nicest guy on the planet, completely shattering the image. : )
(I also seem to recall the entire White Zombie gang bathing in chocolate pudding a couple years earlier, also on Letterman...)