There are so many myths and misunderstandings surrounding sex that I was puzzled as to which one warranted a whole book. It turns out that Dr Brooke Magnanti (previously known to most of us as the blogging call girl Belle de Jour) tackles most of them. She accomplishes this heroic task with humour, skill and passion in a book that is as entertaining as it is erudite.

Magnanti exposes the weak, even non-existent, evidence base for periodic moral panics surrounding sex. She dissects the factoid evidence on the new "disease" of sex addiction, the sexualisation of children, the way pornography humiliates women, the dangers of porn on the internet, the evils of prostitution and trafficking.

Her book should be required reading for all newspaper readers, and for anyone interested in understanding how advocacy research (popular with some academics as well as governments) manufactures findings that are selective, tendentious, dishonest, even incompetent.

For instance, one chapter does a brilliant demolition job on a report claiming to show that the introduction of lap-dancing clubs in Camden, London, produced a 50% increase in sexual assaults in the area, a report produced by people who want all such clubs closed. Magnanti shows that, on the contrary, all the available evidence for Britain points to a sharp fall in rape rates in areas that introduce lap-dancing clubs. Her clear presentation of the statistical evidence, and explanation of what is needed to prove a social trend, here and in other chapters, could be a model for science teachers.

One chapter unpicks the misinformation and wild exaggeration that go into stories of "thousands" of women being trafficked into Britain as sex slaves. One expensive police clampdown did not produce a single case of traffickers in the whole country. To make the operation look less of a failure, the initiative was given the credit for five convictions of men accused of sex trafficking, even though they had all been picked up from other routine police investigations. A similar nationwide exercise in Germany discovered only five women who had been trafficked.

Not surprisingly, the UK Border Agency is far more effective at identifying cases at the point of entry, where trafficking seems a possibility and requires investigation. Yet even here, the total number remains well under 1,000 women, nowhere near the 25,000 claimed by politicians and used to justify the criminalisation of the entire sex industry by the former Labour home secretary Jacqui Smith. In the US, genuinely trafficked women are more likely to be treated as illegal immigrants and criminals than as victims. In both countries, the much larger numbers of people trafficked to provide cheap labour are ignored. They are mostly male, as illustrated by the Chinese cockle pickers who drowned in Morecambe Bay in 2004 when the tide swept in. Somehow, we have got to a point where victim feminism is so persistent an idea that every pea under their mattress becomes a mountain, whereas no one seems to care so much when men die.

Along the way, Magnanti advances some interesting ideas. Myths about sex propagate in the western world because so many (older) people have very limited direct experience. Repressive "moral" policies achieve greater publicity and support at times of economic crisis  as currently illustrated in the US. Pronatalist religious cultures generate the most extreme myths because their focus on procreation as the sole reason for sex leads them to classify recreational sex and gay sex as dangerous perversions. However, the most common problem is what Magnanti entertainingly calls "cargo cult science" as well as advocacy research by interested parties.

The book includes plenty of curious facts. Women earn more than men in the porn industry, in stripping and in sexual services, and they earn far more working in the sex industy than in ordinary jobs. Page 7 fellas, the Sun's counterpart to the Page 3 girls, was distinctly short-lived  like most erotica aimed at women. Kellogg's cornflakes were invented by a man who wanted to reduce sexual desire. A 1918 Sears catalogue advertised a vibrator as "very useful... for home service".

Magnanti is not an expert in sex research nor a social scientist, and so gets some things wrong. She relies too heavily on her experience, which is no doubt why she criticises the stereotype of women's lack of sexual desire. In fact, the evidence from all national sex surveys points unequivocally to higher sexual motivation and lust among men generally.

At the end of the book, she turns to the question of who creates these myths about sexuality and why they are so popular. Like me, she identifies an unholy alliance between rightwing patriarchal men, evangelicals and radical feminists, who are not only anti-prostitution but anti-sex and anti-sexuality in any form. She goes further, to show the lazy complicity of the media, which welcome scare stories, whether true or false, and the tendency for "feminist" women to lampoon any woman who offers a new perspective, as she has done.

Magnanti offers a pretty sharp analysis of sexual politics: who fabricates the myths and why, the role of both rightwing and leftwing media in building up moral panics, the vast sums obtained by the pressure groups that profit from them, and, more recently, too, by the pharmaceutical companies that plan to profit from newly invented sexual "diseases", such as female sexual dysfunction (which simply means women's lesser interest in sex). She details the large amounts of money  more than $1bn on her evidence  wasted on government initiatives directed at non-existent sex problems. These myths are costing us all a lot  financially and in other ways too. Magnanti's critique of the puritan ideology that still surrounds sex is a timely, persuasive read.

Catherine Hakim is the author of Honey Money: The Power of Erotic Capital (Allen Lane).