Dead concerts were like a 3hr sound check
This is a remarkable overstatement. I caught around 35 or so shows in the 80s-90s (not many, by the standards!): While there certainly was unevenness, shows ranged from well put together professional efforts to "Wow!" with only a couple of clunkers (all with an excellent sound system).
To each their own -- I don't listen to Dead much anymore -- but I suspect anyone who equates then with a bar band either hasn't seen much of the Dead, much of bar bands, or not much of either.
Interesting question, how the Dead wandered into a Floyd thread.
John