However, if you try and enter the dungeon while in any quest vehicle (the moose you have to return to the Thunder Totem stable master, for example) you aren't ported inside.
You can then mouse over your group mates and see which dungeon you got. If you don't like it, you leave group and no debuff! You then only have to wait 15 minutes to re-queue due to the timer in the dungeon finder window.
TL;DR:
- Dungeon pops
- Be in quest vehicle
- Accept dungeon queue
- Mouse over groups mates, determine which instance
- Leave if you don't like it
- Find another group in 15 minutes instead of 30