Rath on 24 May 2012
That's not really the definition of a troll, just somebody who is a poor conversationalist.
A troll is somebody who posts with the intent of causing anger in others and they may have none of the charactersitics you posted. They could post a very articulate argument with no abuse at all. However that argument could be something like 'Why I think the holocaust was good' which is bound to illicit angry responses.
Best way to spot a troll is simply to think "Is it likely he/she is posting that just to annoy people"? Of course given the genuine stupidity of some people on the internet (for example the entire YouTube comments section) means it can be hard to judge...
