I am not paying much attention to people being silly. I've had a copperbell mines run where both dps kept calling me a bad tank, and I know I probably didn't do everything perfectly (I'm relatively new to tanking). I also know that THEY sucked since they did my standart job. a dps does not run in first. a dps does not keep attacking when they have the aggro. a dps does not kite the boss away from the tank.
I'm not perfect, but I'm no idiot. I figure out what I did wrong without people like THAT telling me I suck.
if all else fails I join a good linkshell/free company that loves me on my whitemage or bard, and willing to be patient if I ever decide to 'seriously' tank
but back to the topic and 'idiots'. I tend to be friendly when someone doesn't know what's going on. I usually try to ignore meanies and hope my 'good example' rubs off on them. if it doesn't then I hope I never see them again and they stop playing so they can't be mean to others who get discouraged by their behaviour.