Well, in the context of the submitted text, the matter seems different: the section «Be Polite and Kind to Your Customers» expresses a different direction in that very title, and the anecdotal example is about "an usher that «intended to whip a man», «“Because he said I was no gentleman”»" - which (also) heavily suggests that the writer may have omitted some details about "what actually happened".
So, about «accepting [which] customers», well do your Cost/Risk/Benefit calculations; about behaviour, good sense be the ground and in case of controversy add more of the same.