I wish I had a super-upvote.

"OP here" or "Author here" in posts is an obvious one when you see it. (In both cases, it's completely redundant!)

As for comments, regurgitating the input too closely and overusing abbreviations are highly indicative, yet many commenters don't notice.

See for instance (slop warning) https://news.ycombinator.com/item?id=46986273 and https://news.ycombinator.com/item?id=46965103.