We here at Olivia Waite don't believe you can judge a book by its cover, but you sure can judge a cover in relation to the book it's guarding.
Not too long ago, there was a rash of whitewashing in YA fiction which made everyone quite properly upset. Nor was it clear whether this happened because cover designers/marketers had assumed white characters were central without reading the manuscript, or if it had been a more calculated (and thus more reprehensible) strategy based on the questionable idea that books with people of color on the cover don't sell.
One thing I noticed in all this was the widely accepted idea that the cover should be faithful to the contents of the book. And then I read a book that made me rethink that.
The scene depicted here does in fact take place in the story, so I can tell you that the towers are a University for wizards, and the black-clad man is a ninja assassin sent by the Emir to assassinate his younger brother, a new student. The man in pale clothes and, yes, a modern tie, is Corkoran, the University headmaster, who is unwillingly being hefted up by Elda the griffin, and who is about to shrink the assassin down and put him in a rat cage. The black blob on top is another assassin run afoul of a protective spell, and he will be shrunk down as well.
But until you have read the book, this image is so busy that it borders on visual nonsense. The presence of a magical creature fits in with the archaic towers, but the tie is very jarring even though it's very accurate. The goals of the action are far from clear. The human figures look strange and disproportionate. The title text is off-balance and not in a good way, and overall it looks sloppy and amateur, which makes me think the book inside is written in a similar fashion.
And yes, a large part of the trouble here comes down to choices made by the designer: why pick this moment to illustrate? It's a great action scene, but it doesn't do anything in the way of character—especially since it leaves out about five of the main protagonists. Why squish all the words in the title to one side like that? It's faithful to what happens in the story—but only to the events. It's not faithful at all to the tone, which is very simple and frank and conversational, or to the careful plotting, where every character takes action and every action has consequences and even so simple a thing as an enchanted coat-rack changes the course of events.
In short, despite its fidelity to the plot, the cover fails to depict what it feels like to read Year of the Griffin. How then could it attract the people for whom Year of the Griffin is written?
Now let's look at my own very first cover for the forthcoming "Hearts and Harbingers":
The hero I'd envisioned when writing this book does not look exactly like the (gorgeous) man Syneca chose for the cover: in my mind Jasper is more chestnut-haired, and slimmer. But I really, really like the look of this black-haired dude with his beefy arm, and I imagine the woman he's holding feels safe being surrounded by all that strength. You can tell by the tender way her hand is reaching up to caress his face. It's an unusual pose, and strikingly intimate.
That combination, power and tenderness, is something I was very much trying to put into the book as a whole. And people who see this cover are going to get that feeling, and pick up the book in search of it. And that's precisely what I want. Quibbling over shades of hair color seemed a waste of time—and this way there's kind of a fun little daydream I get to have where there are two of Jasper ... mmm ...
What all this analysis amounts to is that there are different ways of being faithful to a book when designing a cover. Whitewashing is deplorable not because it is unfaithful to the details of description, but because the main character's identity as a person of color is going to be more significant to their experience than whether they have green eyes and brown hair or blue eyes and blond hair. But staying too close to the particulars of a story can backfire. It's a tricky dance—and through it all, your cover has to charm and entice and stand out from the other kajillions of book covers readers see on a daily basis.
Makes me happy I only have to write books and not design them.