Walter's Theory

What is the main reason why a buyer would choose to purchase a product or service from one sales person over another if their offerings are comparable? The answer to that question has intrigued me for many years as it is the Golden Key to a successful career for almost any profession. The ability to persuade people is such a valuable asset. One man impressed me with his answer to this question and Walter's Theory was born. I hope you'll enjoy trying to prove or disprove this theory as much as I have.