I might be a weird person of this story.
Returning player here, after years of dps I decided to give tanking a try. Grouped up with a buddy (new player who only ever tanked and now was learning how to dd), and we ran our new shadows for a couple of HS, which went well. Now we are lvl 22, everything seems fine, so we decide to give it a try and queue in GF - we get Athiss, a 75lvl Sage healer and lvl 21 dps I think was a Sent. We log in, I let sage show me directions, I quickly taunt when needed, and trying to be a good tank to the best of my few abilities. We clear the first boss smoothly, and get to the corner of the ruins where you need to go through 2 elites and some trash around. Unfortunately, before the fp I'd just received my group taunt and that was when I decided to use it. I honestly didn't know that I will get the attention of all the mobs around us. Second dps dies and disconnects to never appear again. The healer didn't manage to save my sorry butt and we wipe. Now she becomes extremely annoyed and starts lecturing me on how she got one of the elites on cc and that I shouldn't break the cc when somebody applies it! I apologize a couple of times, explain the situation but she keeps going that if I don't know something then I have to ask for help. Now, condescendence really rubs me the wrong way, but I am trying to respond nicely, compliment her healing skills and we proceed. Our second dps doesn't reappear, the healer initiates the kick, then she demands that I queue us, despite that she's the group leader. When I point it out, she sais that she couldn't queue, but it's fine and we can do it 3-man. Well... Now, my buddy who's new to dps role is asking what the hell is cc to begin with, I explain it to him, the healer marks the cc, I mark the elite I'm focusing on (just to make sure I understand correctly) and..... during the fight my buddy runs away into a group of mobs, breaks the cc of elite and runs it all into healer before I can do anything (my taunt is on cd, and group taunt, as we'd covered, would attract more mobs from nearby). Healer dies horribly. Now she's really pissed, leaves to the fleet and from there starts raving on how stupid I am to do the same mistake twice. My buddy tries to explain that it was his fault but she's not having any of it! Her last words before leaving the group were "and having two tanks in a vet mode is a big mistake anyway!". (Why she decided that my friend was in a tank spec, I have no idea.) But after all the toxic speeches, we decided not to make anyone else suffer from our incompetency. We pulled out our Quzens on heals and proceeded with both bosses nice and easy, not a single death.
I truly understand that newbies can be an annoyance, but please, don't be like that. Personally, when I accept Vet run with a 20-something-lvl, I do not expect this player really know his class. I do Vet runs as a healer from time to time, not often - because it's a very stressful business. But I'd never expect good gaming, gear, class knowledge as a given. The chances are totally random.