Are you able to brush it off when a customer is rude to you, or do you take it personally? Assure the interviewer that you can keep professional composure when it comes to rude or demanding customers.
"I have spent many years working in the restaurant, hotel, and other customer service based industries. I do not take it personally anymore when a customer is rude or difficult. I will do my best to make them happy, but I fully understand that you cannot appease everyone."
"I handle an upset customer with utmost care! I listen, and do my best to help fix whatever issue they feel is upsetting them."