Comment by rdl

What I do personally is keep a (relatively short) file of hn usernames I find particularly good and those I find particularly bad. I go and read comments from those I find good sometimes, in addition to encountering them through the normal course of articles.

The bad ones, I reevaluate whenever I see another comment, but I've never yet seen a good reason to remove someone from that list. Sadly they never seem to end up hellbanned. It's uncorrelated largely with agreeing or disagreeing with views; it's just that there are a group of people who are, as the OP said, really negative, irrational, and destructive to civil discourse.