When you are waiting tables you are the restaurant. Everything about you will impact their perception of how a place is. First impression is usually a lasting one. How your guests are treated by “the restaurant” is how you reflect the feeling of the establishment. If you are friendly and cheerful, then your guests are more likely to feel that the establishment is a happy one. People like to do business with happy satisfied people. The perception is that you like your job, you like the people you work with, and that you are a good person yourself. If you came up to my table and you were perceived to be in a bad mood, my experience as a patron goes down. Nothing is memorable about the food anymore because you didn’t want to let yourself remember a bad time. You only note the food if you are having a good time. There can be exceptions, but it has to be excellent in order to grab your attention.