This has probably been mentioned already, but I'm gonna put it out there again:

I had an unfortunate experience yesterday with the LFD tool that seems like it ought to be fixable. My cleric has sufficiently good gear to heal and dps tier 2 dungeons, but my tanking gear is definitely not up to par -- it's good enough for t1 but only just.

So I join the LFD queue for a random tier one and tier two, checking off tank, dps, and healing. I figure the tool knows my toughness isn't good enough for tier 2, so it won't match me as a tank in a tier two dungeon. WRONG!

We muddled through with me being a miserable tank, but it was a struggle.

So the LFD tool should be smart enough not to do that. Or at the very least, the "ready" screen should tell you what dungeon you're about to join so I can say "hell no I'm not 'ready' to tank a tier 2" and not inconvenience the rest of the group.