What's wrong with some employees?

The other day my wife went to a small business discount store. She has been going to the same place for a while and I did too. She had to exchange something and the person on the counter acted like it is going out of his pocket that he had a hard time exchanging. He kept on making one excuse after another and being sarcastic about her every answer. She later did complain to their offices in New York. Now my question is why some of the employees especially in small retail stores are be so unprofessional and uncooperative. If they have something going on in their lives, they should not come that day to their jobs and not share their miseries with the rest of the world. First, in this economy jobs are scarce and once you get one you try to act like a miserable lot then you don’t have any right to work with people. Small business cries about how they are being squeezed in this economy and then they hire these kinds of people who have no manners of how to deal with customers. I guess that the small businesses in these cases don’t care about their reputation and if one thing sells they pray that the customer does not come back again. That is why you see in many small businesses a policy stating NO Exchanges, No Refunds, All Sales Final, Store Credit only. And then we wonder why these small businesses are suffering. Just because they can't compete on price, at least some of the business should have the courtesy of good customer interaction so that their sales can grow and they can retain customers rather than seeing them once in their lifetime.