Certainly the contents can be questioned if the book is how to sell ebooks online. But there are many people who have talents that are valuable to others, yet don't know how to market those talents online. Ironically, the opposite is often true as well... those who can market freezers to Eskimos don't necessarily have the skills to invent or create something. But I will comment that if you want to learn how to make money online - learning salemanship will never be a waste of time.