The customer is not always right

Staff in proper Jarvis bars frown upon the adage "the customer is always right". In fact, "frown upon" is too mild a description for the antipathy such idiotic notions inspire in right-thinking individuals. As has been noted previously, proper Jarvises are a rare breed, so even if a bar is proper Jarvis, the odds are that there will still be plenty of non-Jarvises and even a couple of anti-Jarvises on the premises at any given time. Garabombo in Rome is a proper late-night Jarvis haunt, and bartender Daniele isn't afraid to stick the nut on someone if they're well out of line.