A popular San Francisco bar has signs warning "We cheat tourists and drunks." I recently had the misfortune of finding this successful business plan implemented in a rural pub near Swinside.
My partner recommended we stop there; she had a memorable time there once before. (She later waffled a bit. The occasion had been so memorable that she didn't remember it all that clearly; she may have been at a different location.)
The evening started pleasantly enough. The ale was OK, although it tasted a bit watered down. When I gave the bartender a twenty pound note to pay for another round, she gave me change for a ten. I insisted I'd given her a twenty, she insisted I'd given her a ten. It was pointless to argue.
We left soon; the patio had become infested with blathering yuppies and their screaming children. Caveat emptor.