Carey Mulligan's face is about to become as ubiquitous as Nicola Sturgeon's as the film of Thomas Hardy's novel, Far From The Madding Crowd, attracts flocks in the coming weeks.

I've only seen the trailers, but Mulligan's portrayal of Bathsheba Everdene certainly captures some of the spirit of this often vexatious woman, who managed to create an emotional hurricane in a sleepy English vale where previously the main excitement had been harvest time and the hiring fairs.

While a great deal of thought has gone into the casting of a story already well known, less attention seems to be paid to the surroundings in which the action takes place. The picture-perfect, tourist-friendly village and town life the director of Far From The Madding Crowd presents, for instance, is almost laughably sanitised. The streets of Casterbridge are clean as a dentist's hands, and the clothes of the villagers and farming folk more like an advert for detergent than apparel recognisable to any clarty Wessex worker of that era.

It's a universal problem. Adaptations of Pride & Prejudice, Jane Eyre or Vanity Fair generally give the impression that road-sweepers worked night and day. The chocolate-box townscapes in Poldark, or Barchester Towers, or Mill On The Floss represent nostalgia for a past that never existed, a Hovis-view of our forebears' lives that for some reason we like to imagine was simpler, and more wholesome and perhaps even a little more enviable than our own.

Of course, novels of the period rarely linger on the squalor, misery or stench of their backdrop. This is understandable since, unless the story was about social justice, those issues were not their focus. But it is also because to Hardy or Eliot or the Brontes there was nothing noteworthy about their environment, which to them was as unremarkable as noxious traffic fumes and the flotsam of polystyrene and tin cans in the gutters are to us. Just because a novelist did not fill in a scene with slop buckets, middens and the disfigured or deformed, however, does not excuse filmmakers for failing to hint at the wider, truer, less attractive picture.

They might argue, of course, that to throw in more than an ounce of realism would be to diminish the glamour of an exercise intended as pure escapism. And yet, more adventurous directors have been known to go to the other extreme, to the extent that sometimes it's necessary to avert one's gaze and be grateful that no smells can escape the screen. There have been adaptations, especially of Dickens or of historical novels such as Michel Faber's The Crimson Petal And The White, that rub our noses in the degradation of the industrial age, and one applauds them, even while feeling queasy. No historical backdrop has been more noisomely and authentically recreated, though, than in Deadwood, a sadly shortlived American TV series set in a frontier town in the late 1800s. Graphic to an almost grotesque degree, it could be said that the scriptwriters revelled in the repulsive potential of their unsavoury location and characters. This may explain why the series did not flourish past three seasons. Even so, it was heroic.

I say this not because I have a cast-iron stomach or a love of the seamy or squalid but because, whether it is Thomas Hardy or Hilary Mantel whose tale is being retold, the story has its roots in the very thing that we are not being shown. In Hardy's time, the reckless actions of a woman like Bathsheba spring partly from the ever-present threat of disease, destitution or death. When life was likely to be short and unfair, and since the here and now might be all anybody had, it was lived, by some, at a sprint. Even the appalling lengths to which royalty and aristocracy went to keep their positions and to ward off commoners whose very breath could contaminate had its origins in primitive fears over survival, and hardship. Thus, while an element of airbrushing by modern filmmakers is understandable, to disinfect the entire setting is also to kill the germ of the story itself.