lag/dodging is one thing that you just have to live with IMO. Some people use it as code speak for I suck at the game, but otherwise it can be a legit reason. Its no big deal.

Other things, however, can be a really huge PITA. Like explaining to people that have "cleared" T4 that you shouldn't stand in front of the Dreadnought. People who have "cleared" Titan X that provoke him while they and the entire raid are behind him >.> . Tanks that know how to "Speed Run" that flash once. This are all things that if they happen once, hey its no big deal. If you explain it a few times and they blatantly are not listening or use don't understand what is happening, then that is a huge annoyance.