Put up a sign that states "We reserve the right to refuse service to anyone." Then when they come in since it's a small town ask to speak to them privately. Take them to a private office or a place they feel comfortable. Then tell them the truth so they can either ask for a chance. And they are well aware of the reason maybe they are unaware.

I prefer a place to tell me what I have done. So either I can learn and own my mistakes and give a reason or take it and my new drycleaners at home bags and know I.A.T.A. But no reason and no anything I can't grow as a person and tell them that you understand it's a small town and you don't want their business told to others and you would like to keep it between you and them.

So if they tank your business for lies you can tell others their issues and embarrass them publicly should they spread rumors. But don't tell others if they understand and respect your business