A business can reserve the right refuse service to anyone as long as it's not based on race, color, religion, or natural origin. Some reasons for refusing service is:
■Patrons who are unreasonably rowdy or causing trouble
■Patrons that may overfill capacity if let in
■Patrons who come in just before closing time or when the kitchen is closed
■Patrons accompanied by large groups of non-customers looking to sit in
■Patrons lacking adequate hygiene (e.g. excess dirt, extreme body odor, etc.)
In order to get around this race, color, religion, or natural origin clause, one simply has to state another reason for refusal of services.