In the absence of a control Joan, we can't be certain that the face of the comedian Joan Rivers, after countless procedures, amounts to one of the most effective warnings imaginable against cosmetic surgery.
Maybe if we could see how her face would have looked, naturally, at the age of 78, middle-aged women would contemplate Rivers' soaring eyebrows, cat's eyes and those stiff planes that prevent a pair of inflated cheeks collapsing on to a mouth that is not so much trout as platypus, and conclude that, yes, hers is definitely an improvement on the conventional package of furrows, sagging jowls and turkey neck - a masterpiece of cosmetic surgery.
Hasn't another brilliant American, Nora Ephron, said that one of her biggest regrets "is that I didn't spend my youth staring lovingly at my neck. It never crossed my mind to be grateful for it". And yet: Joan Rivers? Even with a smooth neck? Now she has been kind enough to film the latest adjustments for a TV reality show, viewers can judge for themselves.
While the industry worries about the rights and wrongs of advertising eternal youth, Rivers demonstrates how it might look.
In fact, in the absence of long-term studies on cosmetic surgery outcomes, its potential victims owe Rivers, along with her fellow guinea pigs, a debt of gratitude. Like the ring-necked members of the Karen tribe when trotted out for tourists, the women must know their appearance will invite as much horror as fascination, but their sacrifice helps save others from a similar fate. Were it not for Rivers' permanently agonised mouth, British TV presenter Anne Robinson's startled stare, the remains of Priscilla Presley's face and a host of fluctuating celebrity bosoms, how many more women would believe the doctors' assurances that their interventions really can, as the well-known Harley Medical Group in London puts it, "enhance the appearance of the face, both as an anti-ageing technique and as a way to address issues people may have with the way they look"?
How do we know after all that some women don't want to look more like a duck, a cat or a large-breasted fish? So long as that seems remotely plausible, women, rather than their surgeons, can be blamed when the experiments go awry.
What you can't tell from the inspection of famous survivors is how much of this ongoing human experiment is completely safe. Or even 50 per cent safe.
For years, in Britain at least, cosmetic surgery's considered advice to women - caveat emptor - has worked beautifully. It survived, untroubled, the publication of a damning 2010 report from the National Confidential Enquiry into Patient Outcome and Death, which exposed shoddy regulation and terrifying inexperience in the industry, along with a general indifference about the mentality of patients, who rarely saw a psychologist before being approved for surgery.
Studies suggest that 5 per cent to 15 per cent of those who ask for cosmetic surgery will be suffering from BDD - or body dysmorphic disorder - which some doctors consider an actual contraindication for surgical treatment, since sufferers may simply go on to develop different bodily preoccupations. The report did not, however, challenge the ethics of surgeons who slice into healthy, physically normal people. "There is nothing wrong with cosmetic surgery," it began.
"People are and should be as free to pay for surgical treatment for what they see as physical imperfections or the less attractive consequences of ageing as they should be free to seek treatment of pain or significant disease."
For instance, any woman could, if she wanted, ask a doctor to perform FGM/C (female genital mutilation/cutting) if, like millions of others, she decided that the original arrangement is unsightly and unlikely to get her a husband. Probably - although from British purveyors of buttock implants and dodgy silicone you can never be sure - this would be a fairly big surgical ask, since the World Health Organisation describes the redundant surgery as a "violation of the human rights of girls and women" which "reflects deep-rooted inequality between the sexes and constitutes an extreme form of discrimination against women".
A link with cancer fatalities is still, mercifully, unproven, but the use of Poly Implant Prostheses (PIPs) has long been associated with hardening, ruptures, leakage and, in any case, the need for replacement surgery after 10 years.
As for degradation and physical integrity, cosmetic surgery websites consistently present pictures of smaller breasts, prior to inflation into large ones, as if, like some vast goitre or missing digit these were manifestly problematic. At the Westbourne Centre that employs, in a private capacity, the president of the British Association of Aesthetic Plastic Surgeons (BAAPS), the literature is understanding to the point you might think of engendering pointless anxiety, about "the concern and embarrassment of drooping pendulous breasts which can occur following pregnancy, loss of weight and ageing". But a pair of new, "pert" breasts is no reason for complacency.
"It is common for women to not really know how their labia should ideally look," says the Transform website, introducing its specialist genital services. So how should they look? Here's a hint: "Women's bodies can change dramatically through the ageing process and from pregnancy ... Transform offers female genital surgery loans which include an interest-free, 36-month loan option."
With that kind of generosity to sufferers from ageing genitalia, no wonder Transform is being selective about replacing the PIPs it fitted.
In response to the PIPs scandal, the BAAPS is advocating a flurry of reforms, from better inspections to a ban on advertising and other practices that, its president said , "take advantage of the young and the vulnerable". Is he quite sure? It is as if supporters of FGM/C vowed to stop butchering girls' bodies. What, if cosmetic treatments stopped preying on the insecure and vulnerable, would be left?