Iconic San Francisco seafood joint that's also California's oldest eatery is ... trends now

California's oldest restaurant may also be America's rudest according to a scathing review by a San Francisco food critic who accused staff of calling its diners 'a**holes' and serving raw potatoes.

The Tadich Grill on California Street has been serving its renowned seafood since before the state joined the union and has long been one of the city's landmark institutions.

But it has a 'culture problem', according to MacKenzie Chung Fegan of the San Francisco Chronicle who has accused it of treating customers with contempt.

'If it's common practice to speak coarsely and contemptuously about guests in front of and to other guests, what are they saying about us when we're out of earshot?' she demanded.

Former patrons of the family-owned restaurant include George HW Bush and Emperor Haile Selassie of Ethiopia.

And it was a hotspot in the heyday of Hollywood stars including Bob Hope, Lana Turner, Clark Gable and Cary Grant.

But the liberal newspaper recently dropped it from its list of the best classic San Francisco restaurants, and Fagan doubled down after eavesdropping on a staff member referring to a customer as an 'a**hole' who should 'sit down and shut up'.

'The a**hole in question, besuited in plaid and inebriated, is propping up the end of the bar closest to the door, and he will neither shut up nor sit down,' she told readers.

'I'm initially taken aback by the server's pointed language, but he has a point. This guy sucks.'

But she was more concerned when a server leaned over to confide in her after a family of three got up to leave.

'The fat slob', he says, showing me the less than 10 percent tip the customer left. 'He comes in here, eats cioppino and tips like this? How can he sleep at night?'