From Mudcat FAQ – Newcomer's Guide:

I've said it before, and I'm sure I'll say it many times more: the best way to deal with both flamers and trolls is to ignore them. Give them silence, and they'll go away. They feed on attention - don't give it to them.

Experience has shown this over and over again. The old-timers here have gotten tired of repeating it. But there will always be newcomers who don't know the drill, and will engage in never-ending debates with trolls. The advice is right there in the Newcomer's Guide, but the problem is getting people to read it. Maybe they everyone needs to have their own painful experience before this advice begins to make sense to them.

However, not everyone without a cookie is a troll.

A better rule is Don't respond to anyone who makes you angry. Apply this rule to old-timers as well as guests.