Meh.
To earn the label
troll, I think that what they post should be posted with the sole intent of irritating and disrupting, without having any personal interest in the discussion.
Posting hidden goat.cx/goatse.cx links or dedicating poems to the Führer for {bleep}s & giggles in a Holocaust forum are trolls.
Insane ramblings which are actually made in earnest [example: Shawn the bus arch troll], or mere disagreement [example: most stuff that disappears from amigaworld.net], or personal abuse in otherwise on-topic discussions [does anybody really need an example?], and so on and so forth, aren't necessarily "trolls".
As for my favourite trolls, they're not found here, but when browsing Slashdot at -1. Hilarious, intelligent and elaborate. They make up for the boring crapflooders, "Slashdot editor X is Gay" and "frost pist" people.