I don't generally mind if someone's new and needs to have certain things explained, but if you're not going to try and learn mechanics, that's when I get annoyed and might leave after several wipes.

I mostly play Healer so the things that annoy me most are probably DPS charging into a fight before the tank (probably annoys a tank too) and also tanks with an attitude :P Running Great Gubal Library and the tank charged into the boss fight, I only had 2k/11k MP, and this was whilst we were waiting for another DPS to join as well, as he'd kicked the last one for "not doing enough AOE" so with that little MP I just didn't walk in, he and the other DPS both died, I explained that he should have waited for my MP to regen, wouldn't have taken a lot of time off our run, but he just started yelling at me, so situations like that are probably my most favoured case for leaving.