We just had an incident with a user trolling the site using what appears to be multiple accounts. A few hours ago, they did something similar, but moderators were never made aware of it.
They insulted multiple users in an answer that racked up an impressive 11 "not an answer" flags, one offensive flag, one custom flag explaining the trolling going on, and 8 offensive comment flags. None of these were seen or handled by a moderator, because they all were automatically cleared by the system when the user deleted their own post.
That doesn't seem right to me. Moderators still should be made aware of flags like this, because we probably will want to look into what's going on there.
I propose that offensive and custom flags be left on a post, even after a user has deleted it themselves. If the problem has already been taken care of, that's easy for us to see and validate. If not, we can take additional action, such as warning or suspending an abusive user.