Flagging is for spam, at least that what I use it for. I reserve my downvotes for conversational indecency: bad faith arguments, personal attacks, not acknowledging/engaging the parent post's points.

I'm not sure why spam should be treated any differently than conversational indecency (personal attacks, bad faith arguing); in theory it could all fall under the bucket of "this doesn't belong here", right?

To me the difference is "this user doesn't belong here, go away" versus "this post doesn't belong here, try harder".

Personally, I flag for blatant rule violations such as comments that are filled with personal attacks or spam.

I will downvote comments that are simply low quality, like comments that merely say "^ This!". I don't usually downvote bad faith arguing because it's hard to prove when someone is arguing in bad faith versus just simply having bad arguments.

> when someone is arguing in bad faith versus just simply having bad arguments.

Sometimes the person just misinterprets the conversation, especially if not being a native english speaker, but the responses could get overly harsh and that's a pity because I'd like to see more international discussions here.