If you consider yourself a troll and ever stop to think "Wait a minute...is what i'm doing socially and contextually appropriate?" Then you are the failest failtroll that ever rode the failtrain to failsville.
If anything, the worse a tragedy is the more opportune the time is for trolling. Somebody just broke up with their girlfriend? Lulz to be had are pretty minimal, not much there to be witty with. Somebody just pretended to be a cop, after blowing up government buildings, and shot 60+ teenagers? SO many lulz to be had, lots of things to satirically exploit, huge potential.
I'll tell you right now, one of the funniest pictures i've seen on the net was the original Farcry cover edited with Brevik's head on the protagonist (if you don't remember what the cover looks like its startlingly relevant, so go look)
Trolling is funny because a Human being flails around the funniest when they are in an emotionally charged rage; eg that kid who had his WoW account taken off him (which, btw, is how people come across when successfully trolled)
People who go "Herf derf I would kick their ass if people did this in real life" are the true morons of our age; I can't think of a more intellectually lacking group of people than those who only have enough brain to swing a clenched fist around in response to words. What screams more dumb than "The things these people are saying are rude and socially inappropriate, I SHALL BEAT THEM HEARTILY, as violence is most certainly not the rudest and most socially inappropriate action you can take on a person"?