Most groups are decent and unremarkable, but the bad ones really stand out. I've had everything from single pull tanks with long pauses between, to healers that straight?? never healed at all? and weren't casting either like the number of healers I see just doing literal nothing is baffling??? ...To a tank who kept chain pulling entire hallways when the healer definitely couldn't handle it and didn't chill til 3 wipes and a bunch of complaining later, or the healer who ran and pulled ahead of me (the tank) when my sprint was on CD and then proceeded to run in circles around the room so I had to chase them down to pick everything up, to the run where we wiped TWICE on the dog tree boss in don mheg because no one was taking the tethers despite??? so many explanations????
Wait edit to add my favorite - this one time we had like, a ton of wipes to Forgall in Wiping City, and nobody could figure out the zombie mechanic (that I had explained four times, in increasingly detailed ways, with help from others), and it was just taking out half the group every time. And then FINALLY, after like 4 or 5 wipes, we got it. And this guy. This ONE guy. In the chat. Is like. "So how do you survive that mechanic?" I had to take a second to not actually just lie down on the floor and cry.
Anyway yeah, you run enough dungeons you'll eventually run into some wild stuff
Not much to be done for it though. You can lead a horse to water and all that... and I've never played an MMO were I didn't encounter some kind of off the wall nonsense, barring maybe Archeage and ESO purely because I didn't play them all that much and mostly stuck to myself when I did. I've been guilty of playing pretty badly myself before, too. Nobody's really immune. I pretty much just laugh it off for the most part, at this point.