To be honest, up until northrend heroics I have no problem "tanking" as my hunter, I have deterrence x2 whenever I need to not take damage, volley in mobs faces is not only uninterruptable but highly effective, and my dodge rate is around 30% with monkey on so it's probably better than a tank at that level in the first place.
I still think it would be an easy fix to get this dealt with. Simply cap the armor at certain levels (Say, 20k for heroics as an example) and that way no one can queue as a tank without at least being in tank gear. To prevent people from simply queuing in that gear and switching out, if you remove that gear at any point, you'll be removed from the queue.
It's really something that needs to be addressed, because I'm pretty mild about things like this, but I've had 10+ incidents in the last couple days and its getting pretty silly. Yes, it's fun to 'tank' on my hunter, but I'd much rather other people tank so I can practice actually doing damage, which is what I'll be doing when I get him to 80. I don't think queuing as a "Hunter Tank" will go over very well with anyone
The most recent example was yesterday: Zoned into Crypts, and we had an arms warrior as our "tank". Waited for him to change specs and stuff, and of course hear instead the dreaded "Rdy?" from our "tank"/dungeon guide (lol). Charges into the middle, pulls all the mobs and starts to bladestorm. Dies instantly. Goes "f this" and leaves. We got a clueless DK replacement who again, had no idea what D&D was or how to properly generate threat, pulled horribly for a couple of pulls before we again kicked him and I tanked the entire instance (again) on my stupid hunter.