Can you link me to specific examples of accounts that you think should be banned and haven't been? or of accounts that have been banned, which shouldn't be? I'd like to take a look.
I'd also look at links to specific comments (i.e. dead and shouldn't be, or live and shouldn't be). But that's less relevant because we have to evaluate these things at account level, not post level. For example, banned accounts can post good comments (and we hope users will vouch for those - https://news.ycombinator.com/newsfaq.html#cvouch, and we unkill them whenever we see them), but it doesn't follow that the account should be unbanned. That depends on the overall behavior of the account.
I'd also look at links to specific comments (i.e. dead and shouldn't be, or live and shouldn't be). But that's less relevant because we have to evaluate these things at account level, not post level. For example, banned accounts can post good comments (and we hope users will vouch for those - https://news.ycombinator.com/newsfaq.html#cvouch, and we unkill them whenever we see them), but it doesn't follow that the account should be unbanned. That depends on the overall behavior of the account.