This week Craig Thomson was found guilty in the Victorian Magistrates Court of having fraudulently used his union credit card to pay for the services of prostitutes at establishments including Aboutoun Catering (a Milsons Point escort service), A Touch Of Class, Sydney Outcalls Network and Tiffany's. The details of visits by high-class call girls to his hotel rooms, were luridly interesting. But no one would have cared that much if he had used his own money, or if, at the outset, he had admitted to wrongly using the card and paid it back. It has ended in the worst way possible; Thomson faces jail time when he is sentenced next month.

Former NSW industry minister Ian Macdonald's tryst with Tiffanie in the Four Seasons Hotel in Sydney would have probably have gone unremarked if he had paid for her services. But the Independent Commission Against Corruption found that Tiffanie was a ''reward'' for having organised a dinner between businessman Ron Medich and executives of the government-owned electricity company Country Energy, and therefore corrupt conduct.

In the US, the attitude towards prostitution and politics is more prudish - merely engaging prostitutes is sufficient to warrant resignation - but also more forgiving, so properly handled, such a dalliance need not be a career killer.

Take the case of David Vitter, Republican senator for Louisiana, leading conservative and critic of Bill Clinton during the Monica Lewinski scandal. In 2007 he faced his own interrogation when phone records for Deborah Jeane Palfrey, known as the DC Madam, revealed his number. He acknowledged his ''sin'', claiming he'd already made peace with his wife and God. Apparently with Louisianan voters, too, as they re-elected him.

Others, though, have struggled to get their political career back on track. In 2008, while investigating unusual transactions in his bank account, investigators discovered that Eliot Spitzer, the Democratic governor of New York, had been a client of an exclusive prostitution ring. Spitzer had made a name for himself as an anti-corruption crime fighter both as governor and in his previous job as New York state attorney-general. But he was an abrasive individual whose arrogance won him few friends. His meetings with $1000-an-hour call girls made him a national joke, and led to his resignation. Since then, Spitzer has tried unsuccessfully to run for public office and has had two not very successful stints as a media pundit.

In 1990, Barney Frank, a Massachusetts Democrat, was another readily forgiven by the US public. Frank was reprimanded for his relations with prostitute Stephen Gobie. Years earlier, Frank had paid Gobie for sex; he eventually hired him as his assistant. But Gobie did not give up his old ways and was accused of running a sex business out of Frank's home. Frank was censured by the US House of Representatives for writing a letter of support, but he subsequently won re-election. Frank apologised to his constituents: ''I did not handle the pressures of having a public life, of being a closeted gay man, nearly as well as I should have.''

At the other end of the spectrum are the Europeans, who seem to have a much greater tolerance for sex scandals involving their leaders. It seems that only the excesses practised by Silvio Berlusconi will get the Europeans in a lather.

Berlusconi was humiliatingly expelled from the Italian parliament last year as a result of a conviction for tax fraud, and he's still appealing a conviction for paying for sex with a Moroccan dancer, Ruby Rubacuori (Italian for Ruby the Heart Stealer) who was under 18 at the time.

The lurid details of his bunga bunga parties at his mansion in Milan proved too much for his second wife, Veronica Lario, who this week obtained a divorce, leaving the 77-year-old free to marry his 28-year-old girlfriend.

Despite the soap opera, Berlusconi remains a force in politics. He leads his revamped Forza Italia party, holding talks this week with Matteo Renzi, the 39-year-old leader of the centre-left who is poised to become Italy's youngest prime minister.

There are, of course, other unwritten rules, first among them being: don't compromise national security.

The Profumo affair in 1963, which scandalised Britain and ultimately brought down the Macmillan government, demonstrated the pitfalls for politicians who fall for call girls when unaware of the identities of other clients.

John Profumo, secretary of state for war in Harold Macmillan's administration, was outed for having an affair with Christine Keeler, who was also having an affair with a Russian believed to be KGB and a drug dealer. At first Profumo denied it, and even lied to the House of Commons, but eventually he was forced to resign. The events changed the way the media covered political sex scandals, and shattered the illusion of politicians being bastions of integrity.

There have been other examples, too. Clinton political strategist Dick Morris submitted his resignation after the Star tabloid revealed he had engaged in a year-long affair with a prostitute. Sherry Rowlands claimed Morris had allowed her to listen in on a telephone call from the president. The moral? Don't big note yourself.

The problem for politicians is that there are no hard and fast rules on moral outrage. In recent years, there has been a shift evident by the media's pursuit of former NSW police minister David Campbell over his visits to the now defunct Ken's Karate Klub, in Kensington, where men could meet for sex (not to use the services of prostitutes). There was no question Campbell had been engaging in a private pursuit in his own time at his own expense, but the Seven Network, aired footage, justifying it as in the ''public interest'' because as police minister he had exposed himself to possible blackmail. Media are more likely to post the story now, and find the justification later. Perhaps it will be justified as hypocrisy, the media pointing to a speech or interview in which the politician put family values front and centre. Or perhaps it will be the denial, contradicted by CCTV footage, a mobile phone photo, phone records or an SMS. In a world where electronic fingerprints are everywhere, the best course is possibly abstinence.