My own thought is that bar band PAs don't have to suck. most of them can be set up quite well. Few are. I think it's like when someone decides that they like bass, so they turn the bass the whole way up. The speakers, if marginal, die and then you have no bass. Or more likely, the excessive bass starts to muddy the sound and overall sound quality drops. (And the user has no clue as to why. But he likes bass and is happy.) A lot of poorly setup PA systems are lacking in the midrange. The infamous "smiley face" EQ. (Sometimes it's a frown.) Whenever someone draws a smile or frown on an EQ, it's a sign of not understanding what an EQ is for. Properly setup, it should look more like some missing teeth. (And maybe not many.) I'm probably preaching to the choir.