When it comes to dungeons(using duty finder) i have never ran into a group of people who despite being inexperienced(be it in gear, or just the encounter) that didn't respond well to explanation of whats going on/what to do. I have ran into people who are obnoxious just for the sake of it, but that's another story.

As far as 8 man stuff go(primals etc) if you don't want to chance getting "bad" players - easy! don't go into duty finder or make a group with people you don't know.

The only point where you get to be frustrated at something is in CT(because no full premades atm), even then you shouldn't harass other people.

If you're randomly put together in a group with other people, remember they also didn't choose to be grouped with you and being rude and elitist to them, just because they don't know how to do x or y, doesn't make you better than them - it just makes you an asshole(not targeting anyone btw ).

Realize that this is not your game - it's everyone's game.