There is the old addage 'The customer is always right'. Which would be fine if it were in fact always true. But alas, right or wrong, the customer must be treated as if they were right all the time. That means smiles and greetings even if you are feelin it. I worked retail for many years and would have to say that dealing with customer complaints was the hardest part of my job. I was in a management position so this was a large portion of my responsibilities. In addition to maintaining a positive customer relations image, I think having to work weekends and holidays, late hours and just being on your feet contribute to the complexities and hardship of this job in general.