Depraved is the way to describe perverse behavior lacking moral decency. It's hard to be depraved when you spend your days defining words at your computer, but the mind does wander.
Some would argue that morality is a subjective thing, so one man's depravity is another man's good time. Generally speaking, however, depraved is the "go-to word" when describing perverts and serial killers. Some rock stars seek out a depraved reputation, but it's mostly for show — they can be as dull as the rest of us.