If I pick up a book with spaceships on the cover I want spaceships. If I see one with dragons I want there to be dragons inside the book. Proper labeling. Ethical labeling. I don't want to open up my cornflakes and find that they're full of pebbles... You need to respect the reader enough not to call it something it isn't.
Man is the animal that intends to shoot himself out into interplanetary space after having given up on the problem of an efficient way to get himself five miles to work and back each day.