Tanking requires a certain mentality... it's hard to explain. You have to have thick skin, and also have a streak in you that is a control freak, as well as being a better-than-average player to be even just an average tank. This tends to lead to diva-like behavior, which then puts off healers. Usually if you just explain what you did wrong, it's all good. We've all done that first pull of a dungeon in the wrong stance/presence/lack of righteous fury. Admit your mistake, laugh it off, and be like "Okay that ain't gonna happen again," and then show your skills by getting it right.

It's more than that though. When I tank, I feel responsible for my group, almost like a Dad or a captain of a ship. It's like... I am not going to let anyone hurt anyone in this group, now matter how stupid, awesome, lame, skilled, idiotic, ridiculous, good or bad they are. I really only tank on my DK, and often times I will help out my healer if I see he/she is struggling by hitting rune tap (with glyph for group heals) on cooldown (assuming I don't need to save it for myself).

The crap you take as a tank is something that you find in any game with the Trinity of tank-heal-dps. What's wrong with people is that if they see a bad tank, they know they are completely screwed, you just can't win if your tank is fail. So if on first impression they see you as a fail tank, they're not going to bother with you. It's harsh, but true - but then again most of the time it's just a matter of making a small adjustment and communicating. I would agree the healer you got was quick to pull the trigger there, seems like you probably had someone on a bad day. It happens