Years ago, I heard a story about a group of publishers asked to recommend books for translation. The criteria were that they should be well-written, have literary merit, be commercially viable and have been recently published. One book divided the judges: a novel written from the point of view of a sex-abuse victim who enjoyed her abuse. The women thought it badly written and disgusting. The men thought it ground-breaking and provocative: its explicit content and taboo-breaking perspective were enough to give it "literary cachet". When it comes to sex, the usual rules for judging good literature need not apply.

I recalled the story while reading German author Charlotte Roche's much-hyped Wetlands, a novel that has been hailed by Granta as the modern equivalent of J D Salinger's The Catcher In The Rye, J G Ballard's Crash and Germaine Greer's The Female Eunuch. Wetlands (translated by Tom Mohr; Fourth Estate, £12.99) tells the story of Helen Memel, 18, who is recovering from invasive surgery on her piles. She regales readers with intimate details about her anal sphincter (you will never look at a cauliflower in the same way again), bodily fluids, shaving and general sex life.

Every orifice is explored, every fluid tasted, leaked or smeared. Her fingers seem rarely out of her knickers. Dirty toilet seats are rubbed against, avocado seeds pumped out of her vagina like Thai ping-pong balls and her labia (or "ladyfingers" as Helen tweely calls them) stretched in a way guaranteed to make women want to cross their legs. More The Story of Ugh than The Story of O, Helen's dirt-dodging explains why she has few friends, though no such easy explanation is given for her obsession with sex and fetishisation of filth. Roche feebly indicates that Helen is sex-obsessed because she is lonely, her parents divorced and her mother fixated on hygiene. Even ground-breaking feminists cannot escape the cliché of blaming mummy.

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In publishing, where there's muck there's brass. Robust declarations that match literary aspirations with taboo-breaking feminism are a tried-and-tested publicity ploy. It worked for French intellectual Cathérine Millet's The Sexual Life of Catherine M, Italian teenager Melissa P's 100 Strokes of the Brush Before Bed, and even the home-grown Belle de Jour's Intimate Adventures of a London Call Girl.

Marrying the book to female emancipation also takes these titles out of the erotica sections and into the respectable front at WH Smith and Waterstone's, as Millet's British paperback publisher Patrick Janson-Smith, now at HarperCollins, explains: "The people walking into shops to buy a book like Catherine M feel a bit less concerned about being seen buying an explicit book if it has literary cachet."

The success in their native markets is part of the blag. It adds a gloss of sophistication, even exoticism. "There is a literary cachet given to foreign works translated into English. It's just another form of literary snobbery," says erotica author Mitzi Szereto. Szereto, who edited The New Black Lace Book of Women's Sexual Fantasies, adds that "Had Wetlands been written by Tracy in Romford, I doubt anyone would have taken it seriously as a work of literature." I detect something seedier behind the hype. Consciously or subconsciously, it perpetuates stereotypes of Continental European women once promulgated by 1970s porn. They may be clever, these Italian, German and French girls, but oh Miss Jones, they ain't half dirty bitches.

Many women publishers agree, though few will do so openly for fear of ridicule. "All the normal rules of publishing go out of the window when it comes to sex, it can be a badly written book, with poor characterisation, but it will be regarded as literary because it is obscene," says one leading editor. "What is depressing for many female publishers is that the current atmosphere of gender politics has taken away our right to say 'I don't like this', because if you do, you are immediately labelled PC or lacking intellectual depth."

Her objections will not worry Fourth Estate, part of Rupert Murdoch's HarperCollins book-publishing empire. It looks to have hit pay dirt with Wetlands. A media sensation when it became the most talked-about book at last year's London Book Fair, Wetlands has already topped the German bestseller list, selling almost 700,000 – mainly to women. The hype has since reached across the world and turned Roche into a global literary sensation.

But Roche is adamant that she wrote the book with a feminist agenda in mind. "The first thing I wanted to do was write a really honest book about the female body, especially all the taboos, and everything we think is embarrassing about ourselves," she says. Helen is a heroine of our times, she maintains; open, honest and flawed. She is not a role model but a celebration of "real women".

The danger with having a manifesto driving a character is that, instead of a girl with a one-track mind, the lead character is reduced into a one-track girl. What may start out as a strong voice becomes monotone.

Helen knows how to talk dirty but lacks emotional leverage. She is not helped by coy references to women's bits, such as "pearl trunk" for clitoris. Maybe they work better in the original German.

Helen's motivation is just one of many black holes through which Roche's readers are apt to fall, if they haven't given up after being plunged into what she acknowledges with glee as the first of many "disgusting bits" in chapter one. Helen's sexual activities, which occupy almost every page, are described with the mechanistic detail of a car manual.

As with all porn, the relentless repetition of sex act after sex act leaves little room for character development. Helen becomes as objectified as the women paraded in the pages of Readers' Wives.

Claims that Roche is challenging notions of female sexual expression are undermined by Helen's age: she is yet another barely legal girl "discovering herself". Yes, her addiction to her secretions is different, but shown through the filter of an almost sociopathic sexual obsession. It reads like something from Alastair Campbell's youthful stories in Forum. To claim that the sexual confessions of a nubile girl are a breakthrough for women is disingenuous. This has been the currency of erotic fiction since The Story of O, never mind porno in print and film.

Evidently, this appears to be a sore point. Roche robustly rejects accusations that she is pandering to male fantasies. She chose a teenage cipher for her manifesto because "it is such a magical age". Her claims are undermined by the fact that she seems to appreciate male feedback more than female about the book. She boasts that men tell her "all the time" that they were turned on by her book. On the other hand, women "wouldn't dare to say that it turned them on". When I point out that maybe they aren't being coy, but just didn't find it arousing, she seems flustered.

Instead, Roche talks about female masturbation, the gist being that women either don't do it or only do it for men. They certainly don't talk about it in Roche's universe– a point that seems, in Britain at least, at odds with countless magazine articles for women, whole episodes of Sex and the City and record sales of the Rampant Rabbit. Again, when I point this out she seems lost. Sex and the City is a fantasy, she says. But isn't Wetlands fantasy? "Yeah, but that is for me sitting there thinking of these things, being really creative and individual," she says enigmatically.

It is this kind of logic, underpinned by a book relentless in its detail and joyless in its treatment of female sexual appetites, that undermines Roche's intellectual claims. As with so many literary sex objects before her, Helen's rapacious sex drive comes from a place of pain and not passion. In the end, Wetlands reads like any other wank mag. It is a point that Roche does not entirely dispute.

"When I started off, I was always sitting in German TV shows saying: 'This is a book for wanking, for men and women.'" She says this with such dramatic relish, like someone being really naughty in front of the camera, that it makes me realise why her status in Germany is likened to that of Davina McColl. She could be egging on the crowd outside the Big Brother house.

Her failure to convince me will not stop some believing that Wetlands is on a par with the best taboo-breaking novels. This is a Marmite book, one that you either love or loathe. Within publishing, women seem to hate it and men think it is ground-breaking. That shows some things don't change.

Lennie Goodings, editorial director of Virago, and not one to balk at strong content, hates it. "It isn't feminism. It's just shocking," she says. "I don't see why they have to wrap it up in feminism." Over at Canongate, the hugely respected editor Francis Bickmore loves it – though he admits he only read a few pages when it came up for auction.

"I think it is courageous of Fourth Estate to take on this book on," he says. "I think Charlotte Roche is writing Punk Feminism. She is about shocking people. It is porn, but it is also about throwing the cat among the pigeons."

And the avocado seeds and the shaving brush and the haemorrhoids.

Sex, scandal - and success

Anaïs Nin

Delta of Venus, Little Birds

Known primarily for her diaries, which she began writing when she was 11 years old, Anaïs Nin is maybe best remembered as a writer of erotic fiction from a woman's perspective. Writing in the 1940s for an anonymous collector, she produced two collections of stories: 'Delta of Venus' and 'Little Birds'. In her journals she refers to bisexuality and an incestuous relationship with her father. Her lovers included Henry Miller and Gore Vidal, and when she died in 1977 she was discovered to have had a 'husband' on each coast of the USA.

Erica Jong

Fear of Flying

Jong's 1973 novel 'Fear of Flying' coined the term 'zipless fuck' and inspired a generation of women who felt as stuck as its sexual adventuress narrator, Isadora, in their marriages. She denies that the book is autobiographical but admits that elements of it are modelled on her own life. Jong's daughter, Molly Jong-Fast, herself a novelist, says that as a child she was horrified by her mother's 'dirty books'. Last October, New York- born Jong admitted that her fear that Barack Obama would not win the US election had developed into an "obsession. A paralyzing terror."

Cathérine Millet

The Sexual Life Of Catherine M

Until 2001, Cathérine Millet was just a middle-aged Parisian critic, curator and editor who ran a well-regarded journal, Art Press. Then, looking back from a monogamous present on a promiscuous past, she published a graphic confessional account of her many – often anonymous – sexual encounters: "To fuck above and beyond any sense of disgust was... to raise yourself above all prejudice". Her memoir caused as big a stir here as in France. Last year, she followed up with a book about jealousy, 'Jour de Suffrance'.

Melissa P

100 Strokes Of The Brush Before Bed

A 17-year-old in the small Sicilian town of Aci Castello, in 2003 Melissa Panarello published 'One Hundred Strokes of the Brush Before Bed': an erotic novel, supposedly based on her own experiences, but packaged in the form of a diary. The scandalous story of "Melissa P" quickly sold half a million copies in Italy was translated into 30 languages. Since then, she has moved to Rome and published two further novels, neither of which made the same size of splash: 'The Smell of Your Breath' and 'In the Name of Love'.