Ordinary users and commenters should ignore trolls, but administrators and moderators should not. They should use every underhand trick in the book, just as trolls do.
Users only add fuel to the fire. Administrators can extinguish it.
I'm not sure how to interpret "ordinary users". I read several blogs with an actively enforced moderation system. However, they are still personal blogs, with a single moderator who can kick people off, and the moderator can't be there all the time.
What I've seen is that there are long-time commenters who will reply to the abusive behavior of trolls, not taking the bait but calling out the abusive behavior for what it is.
They cannot moderate, but as long-time users they are also not "ordinary." In the cases I'm thinking of, their responses don't seem to add fuel to the fire.
> I feed trolls. Not always, not every troll, but when I feel like it—when I think it will make me feel better—I talk back. I talk back because the expectation is that when you tell a woman to shut up, she should shut up. I reject that. I talk back because it's fun, sometimes, to rip an abusive dummy to shreds with my friends. I talk back because my mental health is my priority—not some troll's personal satisfaction. I talk back because it emboldens other women to talk back online and in real life, and I talk back because women have told me that my responses give them a script for dealing with monsters in their own lives. And, most importantly, I talk back because internet trolls are not, in fact, monsters. They are human beings—and I don't believe that their attempts to dehumanize me can be counteracted by dehumanizing them. The only thing that fights dehumanization is increased humanization—of me, of them, of marginalized groups in general, of the internet as a whole.
Users only add fuel to the fire. Administrators can extinguish it.