Behind every good scandal there is an unspoken promise: this necessary pain will make things better. Scandals make you sick. They leave you drained. They inject poison into the system.
But, in theory at least, they kill off the disease and leave the body purified, strengthened and chastened. Behind Watergate, or Iran-Contra in the United States, behind the paedophile scandals in the Irish church or the slow, methodical exposure of Charles Haughey's misdemeanours, is the belief that it will all be worth it in the end because the destruction of the guilty individual will ultimately improve the institution.
After the initial thrill of the chase, it is this abiding faith that gets people through the arid wastes of an inquisition.
What makes the current scandal surrounding Bill Clinton so different and so confusing is the absence of any such faith. No one really believes that any good will come of it all, whatever happens to Clinton himself.
Monicagate is a moral drama played out at a time when the very idea of public morality has ceased to be credible. It is all form and no content. Instead of morality, there is moralising. Instead of a zeal for what is right, there is self-righteous zealotry. The proper point of a political scandal - reform - is missing.
The only certainty is that when the whole sorry affair is over the American political system will not be better but worse, creepier, more hypocritical, even more grotesquely dominated by image and personality than it is now. The only people who will gain will be those who have an interest in weakening the power of government itself, the big corporations which already set the limits within which democracies must operate.
There is, in the whole business, just a single interesting moral question: who's worse, the prey or the hunters?
Clinton has emerged as a man whose commitment to his political ideals is so shallow that he was willing to risk them for the odd moment of kinky delight, a weakling who chose to lie to his friends and allies rather than take responsibility for his actions, a political incompetent whose handling of the scandal has been unbelievably stupid, and a hypocrite who drops many of his nominees for office (especially if they are women) at the slightest hint of personal complications but then tries to insist on a clear division between public office and private behaviour.
But what's the alternative? Who has come well out of this affair? No one at all. Not the people who started it. Not the people who have investigated it. Not the people who will be charged with debating Clinton's fate.
Normally, for instance, one of the stock heroes of a big scandal that rocks the mighty is the journalist who followed a hunch when it was neither profitable nor popular and set the dominoes falling. In this case the prime candidate for the role is David Brock, a reporter for the right-wing American Spectator magazine who, in December 1993, wrote a story on Clinton's philandering, mentioned a woman called Paula, and triggered the Paula Jones law suit of which Monicagate is the unforeseen offspring.
Brock, however, is looking for forgiveness, not congratulations. He wrote an open letter to Clinton in Esquire magazine last April, confessing that his story was a dirty trick, arranged by long-time far-right activists, which he wrote because he saw Clinton, "the first Democratic president in my adult life, as an ideological threat."
He wrote that the "public interest" tests he had applied in deciding whether it was proper to reveal details of Clinton's sex life were "something of a charade, more an attempt to fashion defences for myself against charges that I was a `tabloid' journalist than they were a neutral set of journalistic principles. I wasn't hot for this story in the interest of good government or serious journalism. I wanted to pop you right between the eyes."
Normally, too, a good scandal has a heroic whistle-blower, taking risks to expose the truth. Here, the whistle-blower is a sneak with a hyperactive tape recorder and the hope of a book deal.
Rather than emerging as a brave martyr, Linda Tripp has come across merely as an inveterate snoop and fanatical gossip, trying to make some money from her hobby of poking her nose into other people's sex lives. The scrutiny has been turned back on her and things which should never have been revealed - her arrest on charges of grand larceny when she was 19, her father's philandering, her messy divorce, her weird obsessions with such things as Hillary Clinton's willingness to use the public toilets in the White House (evidence, in Tripp's mind, of a lack of class and dignity) - have been all over the magazines.
Then there's the other vital role, that of the victim. Recognising the need for a victim other than Hillary Clinton and her daughter, members of the Republican party have tried from time to time to paint Monica Lewinsky as a poor, exploited child. Which was all very well until Monica herself appeared in a six-page colour photoshoot in July's edition of Vanity Fair, posing on Malibu beach, those infamous lips roaring red and wide apart in every one of Herb Ritts's 1950s-style pin-up pictures.
Whatever credibility the image of Monica as a confused adolescent in the clutches of an evil seducer might have had, her willing participation in this all-too-knowing exercise in national titillation utterly destroyed it.
Finally, there is meant to be a steely, incorruptible investigator, not the Smutfinder General that Kenneth Starr has become.
His methods - demanding records of the books people bought, forcing a mother to answer questions about her daughter's sex life - have at times bordered on the maniacal. He has blatantly, and admittedly, abused his power by leaking details of secret grand jury testimony to the press, the object of which can only be political, not legal.
He has openly associated with the most virulent members of the Christian fundamentalist wing of the Republican party, appearing for instance with the loopy Pat Robertson just before the 1996 election. And the combination of Biblethumping zeal with his intense desire to discover and report on the minutest anatomical details of what Clinton did with Lewinsky gives most people the creeps.
So this is the moral desert into which Starr's report will be hurled. No good outcome is possible. Whether Clinton is censured or impeached, whether he resigns in disgrace or carries on, in office but not in power, hardly matters.
Nothing will be reformed. The state of politics and public morality in the world's last superpower will be even worse than it was before.
It is even possible that the right-wing conspirators who started the whole thing will face charges for alleged interference with witnesses in the Whitewater investigation and that Starr himself will eventually be censured for his relentless leaking to the press. Disgrace all around would be a bleak but appropriate outcome to a story that has demeaned everyone it has touched.