It is true that behavior is very important for us. If a person's behavior is good, then it is natural for people to respect him, but if his behavior is bad, then it is natural for them to criticize him in secret and disrespect him, even if not in front. I have seen this especially in the case of one of my colleagues. When he behaved badly with people, many people would come to me to complain or express their regrets and also try to disrespect him.
We all behave poorly from time to time, but some people seem to make it their default. Often it is the people who "demand respect" who are the worst behaved.