It's amazing what people will drop a 5-man pug over and even more what they won't. The run that best illustrates this was one I had recently in the Pit of Sauron. I lost 4 people that run which is quite a lot for any run and the odd part was this was a well geared fast group.
I queued for the instance since I needed to grab some quest items for my battered hilt chain and reforge a sword there. So first thing I did when I zoned in was buff everyone and then run around for ~20 seconds tops grabbing a couple infused saronite bars right at the entrance area. Then I headed over to the first pull skipping along on the right like most PUGs do, made sure everyone was with me and pulled. A DPS immediately dropped and the healer followed.
I guess they were insulted that I would take 20 seconds of their time to grab a quest item, the very reason I was there in the first place. In any case they caused the rest of the group to die which was pretty lame. So I zoned back in and whoever happened to be the leader requeued. I mentioned that the last healer left the group at the start of the first pull so there wasn't any confusion as to why everyone was running back. Maybe I should of mentioned I was grabbing quest items before that, who knows.
We're trucking along just fine, first boss goes down and we are headed towards Krick and Ick when hilarious disaster strikes. I charge an ambushing geist and it jumps at me at the same time. We meet in the middle which just happened to be just over the side of the cliff. The hunter in the group jumped down after me, he must of been crazy, and the rest of the group stayed up top while the other three tanked a loose geist that jumped on the party in my absence.
After the initial oh crap I remembered the poison slinging add that I tend to miss walking up the ramp out of the pit and decided to head over that way and see if I could get out there as well. Turns out I could and I brought that poison slinging add with me. Rounded the corner I had to grab that poison guys cousin and closer to the group I had to grab the rest of the geists and grab that one that was hitting people while I was away.
Took a couple of cooldowns to keep myself up going around the long way without a healer, but I made it and no one died surprisingly. No one left the group either.
I keep pulling the rest of the nasty poison mobs before the next boss when a DPS asks for a short break, which I responded that it was just a couple trash mobs and he could take a moment as we continued. Then the healer asked for a break as well, turns out he got a nosebleed and needed to take care of that.
I can only imagine it was a direct result of falling out of his chair laughing at the tank that flew off the cliff. I quipped that if anyone should of gotten a nosebleed it should of been me; that got a few lols. Healer is back and ready to go pretty much right away and we take out the boss. Couple people die standing in stuff, we rez, no big.
Since everyone is standing around still rezzing and waiting to loot I made the mistake of mentioning that we could skip the next two trash pulls (the two most annoying in the whole place) if we mounted and ran past them as they walked down the ramp. Everyone agreed that would be a pretty cool thing to do. I'd only heard about it in rumors from other PUGs and never gotten to try it since someone always runs ahead and starts the event.
So four of us are mounted and the last dude to rez was still drinking and eating. I head toward the ramp and turn around to wait for the last guy as he was just mounting. The other three kept going right to the top and it was just me and the other guy stuck at the bottom as it was too late to run up.
That didn't stop him from trying though, he ran right into those mobs at the bottom and died. I wasn't in combat so I just flipped to kitty and stealthed thinking I'd sneak up to the other three and clear the way back down backwards. The group on top had other plans and ran back down pulling everything on thier way and died. So there I am, all alone waiting for everyone to come back, two people leave the group. The guy I waited for stayed and the healer stayed.
We got two more right away of course and finished the instance without further incident. So those two that left ran ahead without making sure everyone was with them and killed themselves then quit what was an otherwise smooth run up to that point. Yes I jumped off a cliff, but that was a mighty smooth recovery. Who does that?
Three badges and potential 232 upgrades in less than 10 minutes opposed to a 15 minute deserter debuff and 15 minutes in the queue as DPS on top of that. Both from different servers so it's not like they had something else come up right at that moment.
For the best though I suppose, not the type of person I'd probably want to run with anyway and wipes are a fairly convenient time for people to drop since new people just joining are running in at the same time as everyone else.