Overly idealistic as this may sound, it's really important to stay positive in random groups. Because there WILL be jerkoffs, and abandoning a group due to one bad egg compounds the frustration for everyone else, whatever your role happens to be. If nothing more, it's at least more likely you'll get commended if you stay upbeat, or at least politely firm when it comes to making the run go well for people.
It's a small thing, maybe, and we're talking single dungeon runs that take about 20-30 minutes tops, but games like this one only stay good as long as there are those who are respectful and pleasant and aim to spread that, no matter how many jackasses bumble in.
