Ok, I know I'm likely opening myself up to be flamed into next week, but for the love of the baby Jesus, people, realize that the following question is a stupid thing to ask in a random dungeon:
"Hey guys, I'm only here for X, anyone else here for that?"
Realize that it is not in anyone's best interest to answer that question to the affirmative (I almost always tell my group this "don't answer, just run the place"), as it's just not something you ask. Particularly if you're the tank, no one wants to promote your departure due to you not getting your precious oldschool dibs run. Old school is old, welcome to 3.3, the world of the "20% guarantee".
The dungeon finder purposely makes no distinctions between your main or offspec, as it relates to loot. This has been covered in a gzillion other threads, so I'm not gonna harp on it here. Run your dungeon, hope your item drops, and roll. Remember no one can "take" your loot from you, they can only "throw down" next to you, so generate oppurtunities, hope for the best and, if need be, try again tomorrow, or, in the case of, say, reg-TOC farming (from which this pet peeve was born), in another 15 mins.
Good luck, and have fun.