Feeding trolls

I'll admit to being an internet novice, but I had always heard 'Don't feed the trolls!'.

Never worked ..... there was always someone there to throw them some chum.

Now I've noticed that some gun bloggers are going to start deleting comments from one of the more virulent trolls. I always thought that our tolerance of someone espousing their views was one of our strong points.

If a troll cries wolf and no one listens, how much harm has he done?

pm