I had to leave a group the other night. I joined the group. Asked everyone to gather up to buff - it's Proof is in the Poison so those resists are pretty important - and then watched as one guy proceeds to run down the hall on his own. He proceeds to run all the way to the first fight and immediately die. Annoying, sure, but I wasn't going to leave for that. So I say in text and someone else says in voice that we need to stop running off, gather up and buff. Then the NEXT guy runs all the way to the trigger under the bridge and pulls it. He then dies. During all of this neither one of them has said anything in chat or voice either one. They just zerged ahead and died. At that point I politely excused myself, said "I don't think we can pull this place off...I'm going to head out", and dropped group.
I don't consider myself a snob and I'll put up with a lot of bad play - I'm not much of a twitch player myself so I'm not one to talk about perfect play. Just running ahead and then not even saying anything though? Maybe some people would accept that out of a group but I expect one of two things - either flawless play or communication. I prefer communication but I can live with being in one of those groups where everyone just shows up and does their thing without typing or talking at all. But if you're not having a flawless run then you HAVE to be communicating.