Most trolls I came across and found out who they are were people lost in space, frustrated, lonely, lazy, pathetic individuals. Those "I'm 30+ but still living in mommy's basement" kind of people. They're too lazy to put their own lives on the right track, so they try to drag down others to feed their miserable egos. If you don't let them get to you then it's pretty easy to deal with them. Their weak point is exactly where they try to hurt you, usually.
Too bad people feed them on every news article I see. Even if they know that they are answering a troll. The best weapon against them is total ignorance. In the end they want our reaction, and if we gibe them any level of attention, we become part of their sick game.