After a week in Turkey, a country gripped by a constitutional crisis which is, at heart, about almost banal personal freedoms - what its citizens should be entitled to drink, watch or, most particularly, wear - it was a shock to splash down in our society of almost egregious openness.

Piling through the week's papers, the basement antics of Max Mosley, the bosomy madams who beat his poor old-bloke backside, was almost more information than I could bear.

It reminded me of a cartoon strip that used to appear in Viz called “The Bottom Inspectors”, a ludicrous troop - purportedly based on the ticket inspectors on the Newcastle Metro - who burst into homes in the middle of the night to scrutinise and punish unwary derrières.

Can anyone truly be censorious about what people do with consenting partners in their bedrooms, or even dungeons? Desire unhinges the rational mind, emanates from some secret wellspring and seems to have no lucid connection with our ordinary selves.

The French film Une Liaison Pornographique concerned a woman, played by Natalie Baye, with a uniquely appalling sexual perversion - alas, we are never told what it is - who advertised for a man to fulfil it, met him once a month in a hotel to perform the deed, then went home, liberated of loins, to her suburban world.

Likewise, although 14 per cent of British people have apparently tried sadomasochism - albeit more loosely knotted scarf than gimp suit - there is no evidence that even the most nipple-clamped devotees were beaten as children or are wannabe Josef Fritzls. They seek only what Shakespeare described as “the lover's pinch which hurts as it is desired”.

Nancy Friday, interviewing thousands of American women for her book The Secret Garden, found that a surprising number had fantasies of being raped. In their real lives rape still remained a grim and life-destroying crime, but what they lusted for was a letting go, a ceding of control to fantasy partners who knew exactly what they desired even before they knew it themselves.

What is missing from the lives of so many adults is playfulness. Only in the bedroom can many of us be abandoned, silly, free from rational concerns. At its most transcendent, sex is a mini-break from life.

But most erotic fantasies are so cartoonish and crude that to enact them turns us all into grunting fools. Who can imagine swapping e-mails about elaborate scenarios, schlepping round Marks & Sparks for appropriate costumes, securing a venue and recruiting a willing cast. How hard to try to match that glisteningly arousing image in your head with the mug trees and split ends of reality.

And surely later - when your itch is properly scratched - you would look, sated and sane again, around the room at the hilarious paraphernalia of your desire and wonder what head-fit had brought you here.

Perhaps the Japanese have the best solution to the unintentional comedy of flawed humans creakily acting out strange sexual roles. They have created the hugely popular anime and hentai, forms of cartoon pornography peopled by imaginary, perfect and tireless sexual beings.

Certainly a look at that most mainstream window of British sexual mores, the Ann Summers website, is a reminder of the pathetic limits of our role-playing imaginations. The only dressing-up costumes “for him” are humorous posing pouches in the shape of elephant's trunks or labelled “stallion”.

Maybe this is because men fear looking silly or that the standard female fantasy figures - fireman, policeman, bit-of-rough builder, cowboy, Officer and a Gentleman navy lieutenant - drift dangerously close to the Village People.

Meanwhile, women are expected to don cystitis-inducing synthetic fabrics to perform the most hackneyed of roles: policewoman, schoolgirl, sexy secretary (how little dressing-up initiative must you have to spend £35 on a pair of specs and a black nylon dress?) and the inevitable naughty nurse.

The only surprises were the “commando” (a teeny military ensemble capable of devastating the Taleban) and “gangster girl”, an Al Capone fantasy that forgets no man finds a woman attractive in a tie.

Interesting that the bestseller is a beautician's overalls, the so-called Miss Massage, who demands “access to her client's body with no skimpy towels to preserve sir's modesty” - a new entry into the male fantasy world, a consequence, perhaps, of British men stag-weekending at the clip joints of Eastern Europe.

In Turkey, where the wearing of the hijab, is the cause of frenzied national debate, I was told that “headscarf porno” is the latest excitement - a claim I was unable to substantiate since the conservative AKP Government blocks all internet sex sites. But after watching a 67-year-old man having his bottom inspected, I wonder if that involves any great loss.

As I arrived at Istanbul airport, I fished out my last 50 Turkish lira note to pay the taxi driver. He turned it over his hands doubtfully, then pointed to a diamond-shaped ink marking. “No good.” To illustrate he showed me another 50 lira note, where the diamond was a foil hologram. The banknote was clearly counterfeit. I bunged him some British cash and headed for the terminal.

But what to do with my money? As it was the highest denomination I'd had on my trip, it was either from the bureau de change at Heathrow or a Turkish bank cash machine. But would either believe me? Anyway my flight was an hour away, I had no plans to return and 50 lira is around £25, not a negligible sum.

It was a moral dilemma: to perpetuate a fraud or arrest it at some personal cost? Rather than palm it off on some poor carpet seller - although self-employed folk such as my driver are the most alert about dodgy money - I decided to spend it at the biggest, most impersonal and, presumably, richest shop I could find.

So I bought 50 lira-worth of baklava and Turkish delight from the duty-free, twitching with guilt. Would they check the man's till at the end of his shift and punish him for lack of vigilance?

I reasoned that I could have spent my 50 lira without being aware that I was committing a fraud. But I didn't and I was. So what should I have done?

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