Your phrase "compulsive debunker" hits the mark precisely, but I think you
underestimate the pleasure involved in debunking. These are, for the most
part, people whose egos swell when they expose (or think they expose)
others as fools. They are in essence saying: "I can't be fooled as you
have, which is proof that I'm so much smarter than you." Face it, we all
get a rush from proving the other guy is phony -- only we aren't, to coin
another phrase, "abusive debunkers." It's a pathetic motive but not an
ulterior one.