There are some posters that are just annoying people but actually come to participate in the discussion. I try to leave those.
Then there are some people that have like 3-4 things that they want to talk about exclusively in every thread whether it's relevant or not. Those people can f*** right off onto my ignore list. And no I don't feel like I miss anything, because you can pretty much tell exactly what's going on when they're causing shit in a thread.
Then there are people who you legitimately question whether they're intellectually impaired, and there's no loss there, either.
Also, sometimes I just go back through my ignore list and take a bunch of people off, and see if they're any better. I have several people that have spent a long time on my list who have come back off.