I'm guessing they're gold sellers.

Sorry you had a bad experience. I hope you never run into them again but if you do you might want to jot down all their names. Don't post them here I think there are rules against that on these forums. Not so sure that Zam or FFXIVReal Forums would care tho. You may get criticized but you did the right thing to mention this. I for one appreciate the heads up.

If regular players want to form a guild party offering to be paid to run dungeons they should advertise it in party finder and make all arrangements pre dungeon. There are civilized ways to do commerce after all. Just because we're in a virtual world doesn't mean we have to act like thugs.