I mostly pug dungeons, and in 80% of pug runs had no problems with vet dlc, sometimes it just takes more time and to explain mechanics if someone don't know it, especially for first timers. Had some great runs that way. IMO it's more fun with less exp players willing to adapt and learn than with supergroups (unless you need some achievement).
There are always *** around, who don't know mech and don't listen, instead they call you sweet names.
With @Marvinthebeast. I also PUG most dungeons. Its one thing to look up the mechanics online, its another to experience them in game play. I've had more positive experiences than bad. But I know what you are talking about. Its those groups that you can tell from the first pull its going to be a fail.
At the same time, I've run these same DLC dungeons with guildies. While the success rate is higher, its not amazingly higher. DLC dungeons are just harder. Mix in some bad luck, bad RNG, or a bad night and you'll have a fail. All you get from running it with a guild is a lower chance of someone acting like a jackass on the group chat
I have to say I’ve had pretty good experiences pugging vet dlc dungeons. Granted, I’m the tank so I’m in control of a pretty crucial factor. But even that considered I find a much higher quality of players when I do so. Even when I’m grouped with a player not ready for vet dlc’s it’s usually a player who I’d gladly take them to any other vet non dlc. It seems the truest bad players hide from vet dlc. As of now I’ve gotten solid enough groups that I can say I’ve pugged every vet dlc in game.