sure its called trolling - its where a new forum member tries to aggravate the existing members, or split opinions and cause in fighting, there are whole website devoted to how to "troll", apparently its something of a hobby for many people... the AB does attract a lot of them because as a group we always always always draw attention to them, try to argue with them and then insult them - exactly what they were looking for.
the only way to get rid of them is to ignore them e.g. don't feed the trolls