In my experience, the worrisome specs are the ones that are popular and focused around PvP: many players jump into the FotM spec for PvP, see that they're dealing a lot of damage at the end of WZs and assume that the same playstyle and spec are going to be simply *amazing* for PvE content (I actually met someone that thought that the Shadow hybrid tank spec for PvP was a legitimate PvE DPS spec because, and I'm not kidding, he got better results on the damage charts in WZs compared to pure Inf or pure Balance which meant, to his addled mind, that it was the best PvE DPS spec). PvPers that come into PvE have no clue what they're doing and assume that whatever it is that they are doing is *entirely* appropriate, even if it's getting the group killed or pissing off everyone else.
this. the people i have most problems with when tanking...or healing...are 1) unteachable snobs who think they play better than everyone else, and 2) PVPers who can't PVE to save their skins. if PVP requires more "skill" than PVE, then why do you cause us to wipe on fights that should be very simple? -_- you thought the shadow hybrid was bad? you weren't in the party with the "tank and heals dual spec" sage (yes, that's what they called it) my guardian tanked for once. and yes, they were the healer. and i do believe they only had two heals. it really didn't help they they were wearing recruit gear and were getting two-shotted here and there. i tried to be helpful and teach them what to do, but there was absolutely no way we could have beat the BoI final boss with such a fragile healer who wasn't really a healer.