Yes, of course they can!
We tend only to talk about the great books we know which were assassinated by bad films, but we forget that there is another side to the coin.
Filmmakers are always looking for ideas, and screenwriting tutors will tell you that it’s a hell of a lot easier for an unknown writer to sell a script if it’s based on a published book (and you have the permission to do so, obviously). If the book is popular it obviously helps, but sometimes, all you need is a good screenwriter to identify the kernel of a good story, even if it is atrociously written, and rescue it by turning it into a screenplay.
A badly-written book can still have a great story, or at the very least, a story which is made great by virtue of its popularity. No book would be popular if it didn’t strike some chord with readers. In order to become a bestseller, there has to be some hook which lures all those thousands to millions of readers into its net. Of course, if it’s that badly written, it may not become a bestseller at all, but let’s face it, we all know dozens of examples to the contrary. And why argue with popularity? If readers find something to like, there no use in despairing over the opinions of the majority. Art is not always about execution: it is very often about the idea.
A great team can take a book which veers between repetitive and bland prose to downright awfulness, find the nugget of the story within it, extract that, tart it up, eliminate the silly peripheral stuff, augment the attractive insightful stuff, and make a bloody good film. It should be every novelist’s dream, because nothing else will make a person richer than a good movie based on a poor book.
There are several examples brought to mind. I’m thinking about Twilight and 50 Shades first, obviously. Whatever you feel about the stories, the prose is so dodgy it could offer to fix the guttering on your house for 800 quid. In the case of 50 Shades, the first publicity shot with Jamie Dornan and Dakota Johnson is an indicator that the movie might not be as stupendously vomit-inducing an insult to language as the written version. And loads of terribly irritating chick-lit characters make me want to punch them in the face until brought to life on screen by talented actresses who manage to turn them into acceptable humans (Bridget Jones, Shopaholic et al)
And it’s not all down on the authors, either. Sometimes a book can be published that just isn’t at the author’s best. Perhaps if they had just waited a while, and re-edited, or had a better editor, or a more understanding publisher, their book could have been better – or at the very least, the way they would have wanted it to be. A movie can make it into what it should have been in the first place.
Books and movies are perfect bedfellows, and we should be sleeping around. Authors, make eyes at screenwriters. And screenwriters, take an author out on a soppy date. When we’re all in the family way, we could be making beautiful art and literature together. And perhaps a living.