100% certain. There was a time on live, in karnors, sneaking and behind a mob... Con would still be scowling.

What I can't recall is if they would aggro. I am fairly certain it was just a display bug and they didn't.

more than just KC mobs would show up as scowling was a kunark thing in certain areas, but act indifferent with sneak and/or hide. This has been reported, but implementation and research might be difficult.