Recently we had an unfortunate user who was unable to control his temper and wrote a lot of rude and offensive content, mostly in comments.
All of these comments were removed, poor posts were deleted, and the user was suspended for repeatedly being abusive to others.
We did not remove all comments prior to deleting because once a post was deleted they will only be visible to a few high rep users anyway. Those comments also make clear to them why this user was suspended.
Still, we repeatedly receive offensive flags on comments that were on long deleted posts.
As those flags actually make work for others I'd be interested to hear what we should do with them.