Oh, woe, the randoms... ME3, BF3, PS2, whatever you like, they're blind and more tactically stupid than fence posts. My number one rule of random teammates is to never, EVER trust them for anything. If six of them run through a room, don't consider it cleared. If you see that three guys are camping one doorway, don't expect anyone to even shoot at the guy who's gonna pop through it and kill you. Don't even expect them to die first if they're touching enemies who're rather far from you: the enemies are idiots too and may well gun you down while ignoring your teammates... who may return the favour. People play like they're terrified of everything, even in games with really low respawn times and infinite lives, so it's a surprise when anyone moves up. Nobody can shoot, so even if you are accompanied by that one precious guy who actually both sees and shoots at enemies he's not likely to save you. And of course there's the fact that he isn't worried about whether or not you are between him and the enemies. Then there are the other guys who jump in front of you, never fire a shot while you can see them (ever, not just while they're standing between you and the guy who's about to kill the lot of you), and will rage and teamkill you over and over until you or they quit if you even wound them.
Most of that rage is from BF3, I have to say. ME3 seemed to mostly just be packed with people who had no idea how to play. PS2 has its own brands of rage, induced by troll/griefer asshats and people who just fail to confine or manage their incompetence. We're all sick of being run over or crashed into by people who don't even try to pay attention to their surroundings (though first person view from a tank's driver position is absolutely horrendous as the field of view is only like 20°, and the aircraft have significant blind spots even when using free look (though most of the people who crash into me seem to not use that particular feature)). Four of five of us are sick of being the only ones to leave the teleporter rooms when assaulting bio labs and wondering why we have twenty or thirty allies sitting around in there after we clear the area. Something that apparently only irritates me would be the incompetent leadership. Whether I'm in a small squad or a packed platoon run by an outfit that's got two or three platoons running at a time, I'm getting orders from some random guy who's less aware than the random guys on the ground with me at the waypoint (if anyone else bothered to show up) and probably more cocky and self-important while still having little tactical or strategic sense. And of course half of these people don't speak clearly or have crap microphones. Those people who capped a base (or whatever you want to call them) and ran off? They were in a platoon or squad and their leader ordered them away before the cap was even done. Some of the orders I've been given literally caused me to just sit and stare at my screen, dumbfounded, for minutes just thinking "...What? Why the hell? That... what??!?" Oh, and no one uses or pays attention to text chat. If you're not in their voice channel (or, worse, on their TeamSpeak/Vent/Mumble/whatever server) then you'll likely never get a response at all if you have something to say. If you're lucky, everyone's just using the ingame voice comms.
I feel better already. Isn't ranting great?