Well, last night I encountered both the best and the worst duty finder groups ever, since I picked up this game.
The worst was at Stone Vigil, which I hadn't actually intended to run. The healer wasn't bad, but one of the DPS let his equipment's repair level reach zero, and I frequently found them attacking different targets then the ones I was going after, and pulling aggro. On top of that, they were both Bards and frequently stopped to mess with status effects, whenever they did their attacks stopped entirely, between that and their under-specced equipment, I was actually out-DPSing the Bosses while tanking.
Now to be fair, its not as if I made no mistakes myself, but when the Tank is holding aggro on a boss consistently, and the rest of the party still ends up dying first, you know somethings up. Still, I did the best I could with that group, and even though we didn't finish the dungeun, it felt like they were starting to improve before it was all said and done.
The best group was at Cutters Cry. It was a nice social group, but despite save for bosses we didn't need to communicate at all to breeze through the dungeon. I'd mark the enemies, the mage consistently put the right monsters to sleep, and then I ran in there and used flash until I had aggro, and we'd all proceed to rip our way through the mob like a shotgun blast through toilet paper.
I only died once during that entire dungeon, during the first boss. I managed to pull aggro when the boss started spamming adds, and the healer wasn't quite able to keep up with the onslaught. I had thought the healer wiped right after me, so I went back to the entrance, only to realize that the rest of the party was there, with a boss that still had 40% health.
They still managed to win somehow, which is a real testament to how good this grouping was. XD