Well, I'm not sure this is a real glitch, but i use it all the time to kill low level (40's pvp'd) horde. Also, horde can do the same to alli. The auction house has little sides that you can step on (the entrance) one side has barrel's and boxes, and right next to it (facing south of AH, right) (facing north of AH, left) is a thing with wheels, looks like a carriage. Jump on the boxes and barrels, till your just over the top of it. Jump on to it, and wait for the patrolling gaurds to go. From up there, if the patrolling guards don't see you, you can gank anyone pvp'd. (example, throw a random chain bolt at him, or shoot a bow from up there)
Pics SOON coming **