Producing and selling anything as complicated and hard to pin down as a novel was never going to be easy, but there seems to be more trouble between writers and publishers over covers than over just about anything else. From the annoyingly smug position of never yet having had a duff or even a merely dull cover (though I think the Russian cover of The Mathematics of Love is probably, shall we say, an acquired taste, even without the watermark) I can still see how painful it is to feel that your book isn't being fairly or elegantly/wittily/powerfully represented, and I know plenty of stories where there's been blood on the editorial carpet as a result.
The obvious problem is when the publisher's made a clear decision to sell a book as something the author deeply feels it isn't. Have they mistaken the nature of the book? You'd hope that's unlikely, after all those months of acquiring and editing, but it does happen. More often it's that the cover's trying to push it into an industry pigeonhole which the author doesn't think it fits. Okay, so so your book has more pigeon DNA than it does ostrich or cormorant, but that doesn't mean you want your lovingly bred and raised Luzon Bleeding Heart Dove dressed up (or down) to look like every other pigeon queuing up to be fed in Trafalgar Square.
'But it's not that kind of book' the agonised author howls, probably to their agent (this is one of the ways agents earn their cut). It needn't be literary snobbery (though sometimes it is). The trouble is, Tesco say they'll take 500 copies if it looks enough like Marian Keyes/Stephen King, and Borders will put it in their Christmas catalogue, and neither will happen if the current delicate watercolour evoking a mood of gentle resignation stays. That's fine if Marian Keyes/Stephen King fans will like your book - we'd all love a tenth of their sales, after all. But what if they wouldn't? What if people who'd never buy Marian Keyes/Stephen King therefore don't pick it up, though they'd love it if they did? What if the Literary Editor decides they've just reviewed Marian Keyes/Stephen King and don't want another for a while? And what if the Marian Keyes/Stephen King fans do pick it up, and hate it, and post rude no-star reviews on Amazon about their disappointment? (Believe me, there is no depth of paranoia to which we're not capable of sinking in the last few months before publication.)
I keep meaning to ask my mathematical sister how to construct the formula. Assuming that the author wants a cover that represents the book perfectly in all its multi-faceted, between-the-genres originality, and the publisher wants a cover which sends as clear and single a message as possible so as to maximise the chances of the right people picking it up in the clamour of the 3-for-2s, how big a gap between those two goals can a single design bridge? How many degrees of arc, on the spectrum, are possible before you're no longer joining both ends but falling between them?
It's not for want of publishers trying their hardest: they do want to sell books, after all. And though I know authors who truly hate their cover, and had bitter gall rubbed in the wound when reviews and booksellers agreed that it's completely wrong for the book and does it no good, I do think that as authors we have a built-in problem. It's the same problem that we have with synopses, blurbs, shoutlines on the cover and the dreaded one-line answer to the 'What's it about?' question, which we must learn and trot out at the beginning of every radio interview. (Memo to self: still haven't cracked it for A Secret Alchemy.)
The thing is, it took us 75,000 words, or 141,000, or whatever, to say what we wanted to say. If our writing's any good, we couldn't have said it in fewer. As you discover when you start trying to choose chunks for readings, as well as skipping the dialect bit that's in an accent you can't do, it's agony just having to leave this out, to cut it off there. Not because we like the sound of our own voice (though we do, or we wouldn't be writers) but because the next bit's great, and explains a lot, and introduces his mistress, and... So of course it's agony to have our work reduced to a synopsis, a blurb, a shoutline. 'So reductive,' writers fume. It is, of course, by a factor of 10,000: it's ten words instead of a hundred thousand. But even if someone were to read those hundred thousand before deciding to buy a book then, well, they wouldn't buy the book, would they? They'd already have read it. A cover, a blurb, a quote from a famous author: they must say what the book is quickly, before the browser moves on: what kind of story, what kind of setting, what kind of tone and outcome. And it must promise to deliver, to give this reader what they want if they'll only buy it, whether that's a thoughtful story of a marriage, or a head-spinning trip round the galaxy, or an extraordinary, baffling, life-enhancing torrent of words which will have you clinging to the most fragile of narrative life-rafts. It's a lot to squeeze onto a surface six inches by ten, and a bit more round the back.
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By contrast, if you really want to know what makes us authors very, very happy, see here.