See, I don't consider the awfulness to come from any personal rot, but rather from an awareness of just how awful the world can be. If you aren't blinkered to it, then you can tap it as a resource.

After all, we're portraying villains. We know quite well that we have to be villainous when voicing them and so we'll pick the worst of what we know. Which is (sadly for the world) pretty awful.