I'm no salesman. As a child, I took paper routes to get out of the house. I didn't care about the money and hated asking customers to pay. I also hated school candy sales for the same reason. I guess I didn't get that gene from my father.
Maybe, the next time you pick up a really awful book, check out the back cover and ask yourself, "I wonder if this guy (or gal) can really write one hell of a query letter?"