I believe so. Many salesmen work for years before they learn the secrets of success. Top sellers in my industry have some basic principles that they use in every sale.
Most salesmen fail because of ego.
You must always be honest with your client, your boss, and yourself. If you stretch the truth or lie, you will never be in the top producers of sales. You will be spending your time figuring out what you already said instead of what you should say next. The easiest way to be completely honest is represent a product you believe in. Selling anything less than something you believe in makes you a confidence man, not a salesman.