[AstralStorm]

Troll farm is limited number of people with limited capability. These can be tracked down and shut down, their enployers as well. The effects of a troll farm are relatively predictable which is why they're used. It's somewhat rare that anything really unpredictable results from small scale social engineering of this kind.

[Nasrudith]

I must strongly disagree here about unpredictable results from social engineering. Vladmir Lenin was deliberately let through Germany because they figured he would just weaken the tsar. It is hard to get smaller than one person or more unpredictable in impact with many others.