Last night I ran into The Ruins of Varsoon to finish off the Hadden's Earring HQ I've had sitting in my log forever. Everything there was way gray to me and it was easy. The particular named ^^^ MoB you have to kill in this case, H'Rath (?), pops up when you enter his room.
Something odd happened when I got to the room is in. I ran in, he spawned and I started killing him. Out of nowhere two other players popped up and started fighting him. As soon as I killed him (I got the ding) they went invisible again.
Could it be these are lowlifes sitting there looking to kill a named every time someone comes in and pops him? I assume he drops something nice if he's not gray to you. I would have been totally miffed if they had killed him and I didn't get credit. I didn't think of it at the time or I would have reported them. Even if they weren't looking to KS nameds, what they were doing interferes with other players.