http://www.theguardian.com/science/head-quarters/2014/feb/25/internet-trolls-are-also-real-life-trolls
Shocking. But I can at least appreciate the people that troll and openly admit it when they are doing so (PapaG gets props for this - he mostly readily admits when he's doing it).
I read an article where they were referred to as "Cluster B" personalities. They're pretty easy to spot.