long story short: jade temple heroic, total pug, tank is a DK, starts in total frost presence and spec, doesn't change spec or presence and plays totally wrong. I ditched that group after 2 trash packs, because I simply won't heal a tank in DPS spec.
are my standards too high for expecting an actual tank in a heroic?
Do you do any actual communication with the group or did you just leave? If only the tank was a problem, and the tank was unwilling or unable to address the problem then I would have tried to kick the tank. If you just left, no one learned anything and the rest of the total pug as you put it got to continue to deal with a bad situation.
I don't think its wrong to leave a bad group, but I do think that its wrong to leave a bad group without some minimal effort to make it a decent group.