I remember, when fairly young, dining with my cousin (like me, not an American) in a restaurant in Boston. The meal was expensive and the service was, to be honest, pretty awful (putting it kindly), and certainly not in keeping with tone (or expense) of the restaurant. When we left, she left no tip, and the waiter chased after us, crying, "Lady, in this country it's customary to leave a tip!" My cousin replied, "Yes, and in my country it's customary to receive good service."