I talked to two people who had personal experiences with this man and they both said he was the nicest person. They both were serving him, but he was always nice and appreciative for what they did for him. His act was his act, but in person he was very respectful and nice. One person said that on a flight Don Rickles was in First Class, but saw a bunch  of service members in coach. He told the flight attendant to make sure they got whatever they wanted and that he would pay for everything. He then went back in coach and visited every service member and talked with them. I think really that is why he was so well liked by others in show business. He had a very sharp tongue during his act, but outside of his act he was just a really nice guy.