It is a phenomenon that once seemed unimaginable but Paris Hilton, socialite heiress and symbol of a tarnished age of cheap fame, no longer hits the headlines.
Hilton, whose waif-like blonde form first came to global attention via a sordid sex tape and then morphed into a vast commercial empire, is a much rarer fixture on the gossip circuit.
She is even living with a steady boyfriend in Los Angeles. Her one-time partner in hard-partying crime, Nicole Richie, is now a mother with two children.
Nor is Hilton alone in fading from view. Two years ago, singer Britney Spears was engaged in a public meltdown, tailed by paparazzi that had many speculating she would not survive the attention. At the same time, actress Lindsay Lohan was famed for her partying, not her screen talents.
American film and television seemed to be engaged in an orgy of bad behaviour that spurred a flood of media hand-wringing over the state of America's most powerful cultural export: its celebrities.
But now Spears is back on tour and apparently healthy. Lohan is going sober.
The most popular and acclaimed new celebrities in America are figures such as country star Taylor Swift, a quiet-living 19-year-old. The most talked about hit movie in America, the latest in the Twilight series - New Moon - makes a sub-text virtue of its characters not having sex. Even the market price for paparazzi shots of celebrities has slumped by a third.
Snarky gossip website Gawker summed up the situation with a headline: "You'll miss Paris Hilton now that she's gone." That is going way too far for most people.
But in a world wearied by scandals of the rich and famous, it is the shocking move no one saw coming: America's celebrities are behaving just fine.
Perhaps no one exemplifies the change better than Spears. In 2007, the pop princess's career was hurtling towards a crash of epic proportions. She was a constant feature of the party circuit in Los Angeles, Las Vegas and New York.
She was famed for being photographed wearing no underwear. As her career stalled, she was trailed by paparazzi even as she seemed to be going into meltdown. She even publicly shaved her head and then started dating one of the photographers tailing her.
Eventually she was carried from her home strapped to a stretcher and admitted to hospital.
That was then. Spears is now healthy and on a concert tour, albeit subject to a tight regime. Only two years ago many pundits were forecasting her early death. Now Spears is back on top.
But others, too, seem to have put their bad behaviour behind them.
Hilton - once a fixture on the reality TV circuit - is slipping off-screen. She is in a stable relationship, and her most recent publicity resulted from releasing a new shampoo line. Lohan, too, has a more sedate profile. She faced jail time in 2007, but has reportedly started therapy and stopped drinking. Now most headlines that Lohan generates come from her own tweeting on Twitter.
Cultural experts believe the trend could be linked to the global economic crisis. With millions of Americans unemployed and losing their homes, celebrity shenanigans have given way to more weighty and meaningful concerns.
"The economy has sucked all the oxygen out of the room when it comes to other things. The 'flippant factor' of that sort of behaviour by celebrities has made it appear much more unacceptable," said Dann Pierce, professor of popular culture at the University of Portland.
Blatant excess is no longer acceptable: although many finance houses and investment banks are again awarding huge bonuses to staff, this is in the face of public discontent that would have been unthinkable two years ago.
Goldman Sachs, a focal point for such disquiet, has decided not to hold a Christmas party this year and has banned staff from funding their own celebrations.
Now it seems that public disapproval over the behaviour of the wealthy has spilled over into the world of the famous.
Celebrity interviewer Gayl Murphy also believes that ordinary Americans no longer derive Schadenfreude from the antics of stars owing to the very real problems in their own lives. "People used to like seeing celebrities melt down because it made them feel that their own more stable - but ordinary - lives were better.
"But now people are losing their homes and their jobs. They have their own meltdowns to deal with," Murphy said.
Indeed the most high-profile celebrity scandals of the past year have not involved A-list stars or household names. The sort of media attention in America once lavished on Spears, Lohan and Hilton has instead focused on "Octomom" Nadya Suleman and Jon and Kate Gosselin, a soon-to-be divorced couple who had a reality TV show.
Though such people are hardly ordinary in the usual sense of the word, they are not actresses or rich or singers.
A similar cultural backlash was widely expected after 9/11. At that time, the concept of the "death of irony" and an end to frivolity was much discussed after the tragedy and the emergence of a seemingly scary new world of threat to the American heartland.
"We have seen this sort of thing before in pop culture's response to very serious world events," said Pierce.
But it is not just a case of celebrities suddenly acting more soberly. It is also because, as media organisations sense disquiet over reports of hard-partying stars, they run fewer stories about them.
Hilton has in fact been annoying her neighbours with loud partying. The police have received numerous complaints and the local council has been dragged into the affair. However, although a handful of gossip websites carried the story, no serious outlets have bothered with it.
"At the moment, Britney could walk down the street naked with a chimpanzee and we would not hear that much about it," said Murphy.
A survey by the Daily Beast website revealed that celeb paparazzi photos were now selling for 31 per cent less than in 2007.
"The celebrity media bubble has burst," said Beast writer Nicole LaPorte. That has been coupled with the signing in California last month of an anti-paparazzi law that will punish photographers who invade a star's privacy.
But trends come in cycles. The wave of seriousness in America after 9/11 eventually disappeared, and gave way to an era of wild partying by young stars, culminating in Britney shaving her head and other celebrities facing going to jail.
Now a new frugality appears to have come into play. Yet this, too, will pass and - as Spears, Hilton or Richie look on, older and possibly wiser - a new generation of hard-partying young stars will emerge.
"Give it a year and a half and, if the economy is no longer staring into the abyss, we will see a return to frivolity and a return to an interest in it," said Pierce.
If the good times roll again, so will the celebrities.
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