Authors are deliberately excluded from all this, on the grounds that they're so in love with what's inside the book that they don't understand what the cover stuff is for. Which is advertising.

The purpose of cover art is not to show the reader what's inside the book.

It's to get his attention from across the bookstore and get him to pick the book up in the first place.

Half-naked women and muscular barbarians are very good for getting teenaged readers to at least take a look. Black and red are good, too. And spiffy hardware, like spaceships. Cut-out covers, foil, blood, all that stuff--it gets attention, and the art and marketing people really don't give a damn whether it agrees with what's inside the book.

The cover gets you to pick up the book and read the blurbs; the blurbs are supposed to convince you to actually buy it. The blurb writer doesn't care any more about accuracy than the art director did; his job is to sell the book, period. One way to do that is to skim through the book and pick out all the most lurid details.

So all this is done without the author's interference. The author might put up a fuss about the half-naked women, since everyone in the story is ninety years old and wearing dirty bathrobes the whole time. The author might object to having his sentimental tale of old age cover-blurbed, "Shocking Love Secrets of the Ancients!" Who wants to waste time arguing with him? Better to shut him out and deliver the package as a fait accompli.

-- Lawrence Watt-Evans