Last time I played WoW was three years ago, and from what I remember it was fine, everybody I formed a party with was polite and helpful, even people outside my party who just happened on by would stop and help me kill something or ask if I was interested in trading something, EVEN people of the opposite faction would be courteous and tip their hats as I passed, and who could forget the dance parties on the main street of Stormwind.
But even there you'd find the occasional starfish who would camp your body, or belligerently insult you because he didn't think you were pulling your weight in the party (and this guy was afk in the corner for half of the dungeon run).
So yeah, you'll find plenty of annoying people everywhere.