A lot of people know now that without planning which include CC'ing and careful pulling you are faced with a wipe. Having to explain with each random that healing isn't the same and having a wipe and then getting the all too well known comments of "do your job" "heal please" and so forth is annoying as hell.
Personally i've been finding myself just sticking to healing instances with guild members, people i know that won't get carried away with all these big buffs to their dps and tank abilities.
What does everyone else think? still going to go into randoms and picking healer role to find out that your group will wipe on stupid mistakes and blame you for it?