I have the same problem, i run icc25 11/12 heroic every week which i consider decent, and next to that i have a few irl friends who actually have no guild at all, and spend their time running fail icc pugs or pvp around a bit.
On occasion i join them in icc10 since i dont need anything from there anymore, but it gets old soon when we are on ventrilo and they bitch about every mistake a pugger makes, and then they themselves fail horribly on fights like festergut non hm and laugh about it, not realising they are bad.
I feel your pain OP, my friends also think they are good players while they actually suck.
Then againn, they all play dps.
Best you can do is suck it up, think ''haha you suck'' to yourself and play on. Works for me!