[unrelated to topic]
Always wondered, if someone is hellbanned, how come anyone can see it? In other how did you see it and how did you know he was shadow banned?
A lot of people find this distasteful for obvious reasons, but it's fairly effective. The occasional good posts from hellbanned users (which are the vast minority; most are terrible, spam, or at best noise) are simply a result of that moderators are not perfect.