I have stopped doing all random dungeons on all my characters because of the frequency of getting DLC dungeons. I just can't agree with people who say these are puggable, they just are not in my opinion. You need to be a masochist to try Ruins of Mazz or Cradle of Shadows with a pug. I have never successfully completed these with a pug on normal mode, let alone Vet mode. And that is with a tank that gives everyone a 13k shield every 3 seconds. If there are mechanics more than "dps fast and don't stand in red" then pugs cannot do it.
Does anyone know if there is some way to avoid the DLC dungeons? If I group with 1 person that doesn't have the DLC on his account and we queue for random will it avoid the DLC dungeons?
My final option would be to drop group as soon as I see what the dungeon is.. but since I only queue as tanks that is pretty cruel to people who have been in the queue for an hour.