is there a community for asking specific questions such as “is this user a troll”, “why do people act this way,” “what should I do”, etc.?

I think you're in it

There are comms similar to that for mod/admin abuse but nothing for general users. Though, I think it's a good thought. I was thinking of starting a comm just for things like asking if certain content has relation to shitty stuff/is trolling, because sometimes it's just hard to tell if you're not already entrenched in certain language used as dog whistles and shit. So often I see a meme that appears to be "lol so random" but it just has a certain vibe to it that makes me wonder if it's actually bigoted in some way that I just don't see.

I don't think so. The largest ask communities, according to their own descriptions, say they're for more open-ended questions, albeit AskLemmylemmy.ml seems to be more lax about it (and it seems like maybe AskLemmy@lemmy.world has kinda relaxed on it too).

There's the newer !ask@lemm.ee that doesn't have the open-ended part to their description, so might be a good fit.

You could ask the person directly to explain themselves

There's one about power tripping bastards but aside from that IDK

Yes. There's the .ml instance. If they're from there, they are a troll!

/kidding

Maybe !fediverselore@lemmy.ca