I personally think there isn't any exact line. Everyone has to make that decision for themselves. And something which might be alright in one communicy might be unacceptable in another. Like political debate vs casual conversation vs technology discussion.

I tolerate some mild trolling. I hate argumentative people, at least when they're wrong, don't listen but don't stop spewing their nonsense. I don't accept personal attacks and hatred in general. I don't tolerate brigading, mass-downvoting and such things. And I think we already have enough misinformation available. Any lies and factually false things can be deleted IMO unless it contributes something at some level.

I also despise people wasting other people's time. Baiting with controversial topics and then never engaging in the discussion. Asking for advice and then not reading or upvoting any comments. Dumping content and links from other platforms to make Lemmy be "more active" while actually turning it into a dumpster.

I think mods should be fair. I love meaningful discussions. People sharing personal stories. Learning things. Being nice to each other and doing literally anything constructive with our time here.

I tend toward being liberal. So I try to be alright with as much as I can.

I think most people have a working moral compass. Not everyone, but enough people so we don't really need to discuss what's nice and what is unacceptable behaviour.