Feeding trolls is ok, as long as one realises they are a troll, then the diet of what you feed them can be modified. Since they are trolls, it means they are already close to having already gone totally bonkers. Feeding a troll a big bowl of statements which make no sense at all, and are non-sequitur is most effective. By not joining in on the issues they state and replying with something that totally makes no sense, one can make the troll to self-destruct at a much faster rate. So, it is not so much as to not feed trolls, just be selective as to what one feeds them.