Do players know when they've been marked? I imagine at least their health bar becomes cracked, since it's a debuff, but I'm not sure if that actually happens, or if they can also see the giant dark beam that shoots out of their head. I'm having a hard time figuring out if enemies simply don't know I've marked them, since they don't seem to react at all, or if people just don't realize what's going on and ignore it.

I'm curious because, if I mark someone while sneaking and they can tell, I remain hidden, but I'm also giving them a hint that someone is around and about to attack.