A lot of marketing nowadays borders on fiction. A lot of marketing crosses the border and runs amok on the other side of the truth. Though you write and sell fiction, this isn’t the kind of marketing you want to engage in.
Readers buy a book because it’s fiction, but if the marketing that sells that book to them is equally made up, you burn their trust. That book they bought sells for a few bucks. A single sale is not what a career is made of. You need repeat business. You need word of mouth. You need to keep their trust. So, you need to tell the truth. Make a good story of the truth, of course, but stick to what’s true. Don’t build up readers’ expectation, then turn around and disappoint them.