The word 'troll' is the most massively over-used word in society today.
A 'troll' was somebody who would cause an argument between OTHERS, not argue himself. The best example of a classic troll would have been in the days of Usenet where a troll would crosspost a question about whether god exists between a Christian and an Athiest group. He'd only post once - but the respondants would fight amongst themselves.
Now it seems everyone who argues/doesnt agree with you/whatever is called a 'troll'.
Annoying.
People who post pathetic comments on Facebook RIP pages, people who argue ridiculously stupid points on internet forums and people are who downright insulting for the hell of it are not 'trolls'. They are 'morons'.