'IT'S NO fun playing strip poker with an exhibitionist,' said a character in a recent American film, throwing down his playing cards when his female opponent got too keen. Quite a few people are feeling that way these days about playing the celebrity game with Madonna. What's the point of chasing her the way we like to chase celebrities, chasing her physical and mental nakedness, trying to find her vulnerabilities, her secrets, her games, if she will insist on stripping off and masturbating in front of us?

It's an odd conundrum. After all, every female celebrity is hounded for her body, tacitly or overtly, as the scandalmongers crawl through the undergrowth to take topless photographs; pass around uncertain details about measurements and proclivities; endlessly repeat banal tales about them combing their pubic hair or going around without knickers or consenting to three-in-a-bed sex. Those obsessions can be ignored or confronted. In Sex, Madonna's long-publicised book, which went on sale this morning, the mode is confrontational: she's saying - 'You want the sleaze? Here it is] See how you like it]' And watch the celebrity-lovers squeal, all the way from the American press to the English tabloids to Martin Amis's shocked dismissal: 'the desperate confection of an ageing scandal-addict', and Daisy Waugh's: 'a trashy pop star re-relaunching herself'.

That's one side of it; in publishing this book Madonna is entering a newly open phase. She's making her admirers own up to their real desires, and then, maybe, they won't need her so much. The other side of the coin is the teasing erotics of her sales technique: the details about the wrappings and the covers, the press embargoes, the excessive secrecy, the pounds 25 price tag. That suggests nothing has changed; it's all about more cachet, more notoriety, more sales, than ever.

Whatever the reason, people do want this book. The Observer sold 610,000 copies on its Madonna Sunday compared with its usual 530,000, which makes it comparable to the Diana secrets, which sold the Sunday Times an extra 20 per cent. We're desperate to see it, and we'll take anything - the video with its censor- bands, the media's snuffling, the sneak previews, the gossip. Really, it's less exhausting just to put down your pounds 25 and get the whole thing.

Certainly you'll get value for your money. Sex is a much better coffee-table book than most. Its aluminium covers are rigid and smooth, with a satisfying matt sheen. Every photograph is quality Meisel, perfectly lit, framed, touched up, detailed and expressive. The overprinting and colour washes and layouts are elegant. The content, words and pictures, is just as buoyantly sleazy as you imagined. Here's a taster: 'I love my pussy . . . Sometimes I sit at the edge of the bed and spread my legs. And stare into the mirror and wonder what others see.'

Over the page we do, indeed, see Madonna touching herself while straddling a mirror. And it gets more pornographic - much more pornographic - than that. Although sold as Madonna's own fantasies, Sex is simply a catalogue of well known perversities. Most of the poses are suggestive rather then explicit, but practices gestured at or indulged in include bondage, anal sex, flagellation, golden rain, oral sex with a dog, all kinds of group sex, and a particularly wicked number with Madonna as a 'little girl' in ankle socks and cotton knickers on the lap of a much older man.

But, as so many people have remarked over this series, and over the fluffy Playboy-type pictures published in Vanity Fair last month, it isn't terribly sexy.

Madonna understands that only too well. In one of Sex's texts, she writes: 'I'm not interested in pornographic movies because everybody is faking it and it's just silly. A movie like In the Realm of the Senses turns me on because it's real.' And this book is much, much more faked then your average piece of pornography, because Madonna is so packaged and posed; and you can see Steven Meisel's styling in every frame, even the 'reportage' ones in pizza bars and on sidewalks.

On the one hand, this vanilla packaging is horrible. It's the ultimate colonisation of sex by the stylists, the exhibitionists, the magazine-culture freaks. On the other hand, it's great. By making all these outre sex games into acceptable theatricals, Madonna is doing what only Madonna can do - taking images that are part of our hidden sexual culture, images of violence and madness and degradation, and reclaiming them, making them happy, guilt-free and funny. She is helping to divest women of the mystery that contributes to their lack of control, in thrall to the pornographic subtext of culture. Despite some of her controversial statements about bondage and abusive relationships, it's a straight line from clean-living Seventies feminism to even her kinkiest photos, because Madonna never looks anything but amused, matter-of-fact and jolly.

Clearly, one of the reasons that Madonna is able to legitimise so much of what we feel to be taboo is because of her involvement with the gay scene in America. Madonna loves gays, and they love her. The book opens with Madonna plus some very tough lesbians, and goes on to huge group scenes with Madonna and about 20 male strippers. The visuals owe much to the graphic beauty of Robert Mapplethorpe's sexual images, as well as the strong camp of Bruce Weber; and all the accoutrements and upbeat strutting of gay porn. It is straight out of the toughie sexuality of pre-Aids New York clubs. 'I like gay male strip places,' Madonna writes in Sex. 'Straight male strip places are disgusting. Those guys can never dance. Only the guys at the gay clubs can dance and they always have really good bodies, not real beefy stupid bodies, more slim and beautiful.'

Another reason for Madonna's towering confidence is the joy she finds in her own gender. A vast proportion of the pictures are onanistic and narcissistic, and there are no paeans to the penis to match the vaginal vanity quoted above. Indeed, the most Madonna will say is: 'I wouldn't want a penis. It would be like having a third leg. It seems like a contraption that would get in the way. I think I have a dick in my brain.'

In his Observer article on the subject, Martin Amis wrote: 'If the identikit Madonna fan is still the 13-year-old lookalike and wannabe - then what?' Unromantic though it might sound, it's probably no worse even for them to see all this open, energetic, experimental sex than to yearn over Monroe's wide-eyed vulnerability, say, or the Supermodels' silent acquiescence in erogenous exploitation, or the slick sexual games of Hollywood thrillers, with their perverse and violent subtexts. It may not always look very nice, but in Sex the woman is happy, and the woman is in control.

'Sex', by Madonna, Secker & Warburg, pounds 25