So far, no evidence has emerged to suggest that the disgraced Governor of New York, Eliot Spitzer, was secretly homophobic or indulged in insider trading. Gay websites have been lamenting the fall of an American politician who supported legalising same-sex marriage, leaving it to Spitzer's numerous enemies on Wall Street to gloat over his spectacular demise.

Six years ago, when he was New York's Attorney General, Spitzer accused one of the world's most respected financial institutions, Merrill Lynch, of "a shocking betrayal of trust" over its investment banking practices. He also went after the supermarket giant Wal-Mart for selling replica guns which could be mistaken for the real thing. Even further back, in 1992, he took on the Gambino organised crime syndicate and ended its control of the Manhattan trucking and garment business. So how did it all go so badly wrong?

Spitzer's flaw is in essence the same as Bill Clinton's, an appetite for casual, risky sex which was exposed when Spitzer moved money around various bank accounts as he carried out transactions with a high-class escort agency. (The latter adjective doesn't mean much, by the way; I've never heard of anyone using a low-class escort agency.)

Spitzer turned out to be Client 9 on the books of the unimaginatively-named Emperor's Club VIP and while punters rarely face criminal charges in the US, he may have fallen foul of strict anti-trafficking laws after arranging for a young woman to travel from New York to Washington to have sex with him. If it can also be shown that he deliberately moved cash in order to hide his tracks, he could be charged with "structuring", a felony offence punishable by up to five years in prison.

The difference between Spitzer and Bill Clinton is that Spitzer is rich. Where the former President and Governor of Arkansas tried to get sex for nothing, relying on his famous charm, Spitzer could easily afford to pay for it. His father made a fortune in real estate, later using it to bankroll his lawyer son's political ambitions, and the Governor was able to purchase sex from an escort agency whose most expensive "girls" were booked at $5,500 an hour in cities across the US and Europe.

And while Clinton's career as a serial sex pest led to ugly allegations of sexual harassment and even one of rape, Spitzer thought he had covered his tracks, spending (according to one estimate) up to $80,000 on prostitutes. Federal agents believe they have evidence that he used the escort agency on nine occasions in the past 18 months.

Earlier this week, the Governor took the traditional route of a man in deep trouble and appeared in public with his wife Silda, to whom he has been married for 21 years. She had the drawn, disbelieving look of every politician's spouse who finds herself required to stand by her man when she would probably prefer to kick him in the teeth.

Like Mrs Clinton during the Gennifer Flowers and Monica Lewinsky affairs, Mrs Spitzer is having to come to terms with her husband's other women, one of whom has been giving interviews to American newspapers. Identified only as "Kristen" in a federal affidavit, the young woman took a train to Washington on 13 February and met Spitzer for sex at the Mayflower Hotel.

When he inquired about "Kristen" before booking her for a four-hour sex session, Spitzer was told she was "an American, petite, very pretty brunette, 5ft 5ins, and 105 pounds". "Great, OK, wonderful," he replied. This is supposed to be the classy, safe end of the commercial sex industry, according to campaigners for decriminalisation, but "Kristen" was warned that Client 9 was "difficult".

Like many men who pay for sex, whether with street prostitutes or call girls, he had a habit of pestering women to "do things that you might not think were safe" – widely assumed to be a reference to unprotected sex. What Spitzer didn't know and might not have cared about is that "Kristen" entered prostitution by exactly the same route as many other young women, after becoming a teenage runaway.

She comes from New Jersey, is an aspiring singer and uses the name Ashley Alexandra Dupre although she seems to have originally been called Ashley Youmans; now 22, she says that she has "learned what it was like to have everything and lose it, again and again". Unlike the call girl of male fantasy who lives in a luxurious penthouse, she told the New York Times this week that she was worried about paying the rent on her flat after the man she lived with walked out on her.

Her MySpace profile describes her history thus: "When I was 17, I left home... left a broken family. Left abuse. Left an older brother who had already split... I have been alone. I have abused drugs. I have been broke and homeless. But, I survived, on my own". On Monday, she made a brief appearance in a federal court, and is expected to give evidence against four people charged with operating a prostitution ring.

Most liberal politicians, including Eliot Spitzer, would say that girls like Dupre desperately need help to avoid the kind of exploitation that awaits them when they leave home at such a young age. During his term as Attorney General, Spitzer broke up two call-girl rings and is on record as comparing prostitution to "modern-day slavery", one of many quotes which have come back to haunt him this week.

Despite his abrasive style as a politician, his hypocrisy appears to have been confined to this one area of his life, suggesting that his support for other liberal causes was genuine; it is quite possible that Spitzer liked taking risks, that the 48-year-old politician found that having sex with much younger women in hotel rooms gave a jolt to his libido and was arrogant enough to think that he wouldn't get caught.

The other possibility is that, like a substantial minority of modern men, his sexual attitudes are totally incompatible with the other causes he supports. This is not the early Sixties, when the US President slept with film stars and call girls at parties which journalists knew about and chose not to report, colluding with John F Kennedy's image as a devout Catholic and uxorious husband.

Men like Eliot Spitzer and Bill Clinton are not very different from JFK in their belief that women exist to service them; they think they are entitled to blow jobs from interns in the Oval Office or unprotected sex with prostitutes in the Mayflower Hotel, but they move in circles where such attitudes are rightly regarded as prehistoric.

So they get married, live a lie by parading themselves as family men and eventually expose their wives and themselves to gruesome public humiliation of one kind or another. It happens over and over again, not because their accusers are puritans but because it is no longer acceptable to abuse vulnerable young women in this way.