Since forever.
And one more thing. While we're on the subject of trolls, why do modern trolls utterly suck? In the 90's, trolling was high art. Slashdot trolls in particular were geniuses in the craft, weaving perfectly proportioned delicately scented masterpieces of intellectual turds and dropping them in perfectly chosen locations.
Now, trolling has degenerated to the point that the word itself is misused to mean anyone who post something anyone doesn't like. Any random idiot can now be considered a troll. It's a fucking travesty. Trolling is NOT just annoying. It's careful, deliberate artwork.
What happened to it?