I'll often come across shadow banned comments, and when I look at the author's post history (back to the first dead comment, plus a few pages of comments before) I really don't see anything wrong. Is it because the comment(s) that got them banned have been removed?
When I run across such an account, should I email an HN mod to investigate? I wouldn't mind doing that, but I've tried before and never got a reply back -- so not sure what the outcome was.