It’s unavoidable, really. In certain kinds of businesses—a bank, a retail store—a certain kind of customer can easily turn a good experience into a bad experience for his or her fellow customers. Nevertheless, it’s the business that will be blamed. In this article from Business News Daily, the author suggests that it is inevitable that a “bad” customer will wander in some day. They have a problem child. They take up a lot of an employee’s time with endless questions. They get ticked off about something loudly enough for everyone else to hear. 

A good customer service mindset, coupled with good employee training, can at least mitigate the negative results of such customers on others.  A good employee training program should alert front line employees to be on the lookout for problem customers and to have some techniques for dealing with the situation quickly and efficiently.  Providing a good, overall positive experience for everyone in your business should be the ultimate goal.