Here's an anecdote. At the weekend I did a lot of pugging on my Holy Pally to gear him up. Chime! Stonecore. Groan... I never have high expectations of Stonecore pugs, but then I noticed the other four in the group had matching guild tags, and that those matching players had several epics each. For the win.
When halfway through the run I am presented with a roll window containing a BoE Epic world drop worth approximately fifteen thousand gold on my realm, of course I wait to see how the others in the group roll, as I've learned too many times that rolling Greed early in a pug is the best way to get your loot Ninjad. So I wait. Twenty seconds pass without a word or a roll. Two people roll Greed, so far so good. The rest of us wait... the timer ticks down -- like a game of chicken. With seconds to go, the Warrior rolls Need. NOT ON MY WATCH. Needed! And it's mine.
"Ninja!" the party cried, knowing full well I had only followed the precedent set the by the Warrior before me -- the warrior who was their guild-mate. In fact I'm the one who should be outraged when he tried to ninja it. I quietly celebrated and prepared for the boss pull.
So what lesson can we learn from these shenanigans? [yes I like that word] The answer is: roll Need. You idiot. Ninjas exist, and playing by some made-up moral honor code in the wild anonymity of a pug is going to get you exploited. When everybody Needs, everybody is treated fairly. It's like the Prisoner's Dilemma but without any penalty for mutual defection. So please, save yourself some impotent outrage and just Need.
Now the only thing I have to figure out is if I was the last to roll and they did all Greed whether I would have then done the same. I suppose it's an interesting point in itself that in all the pugs I've done I've not yet had to make that decision...