When Kylie Minogue became the face of Australia's breast cancer campaign, the effect was good.
And it was bad.
It was good because it raised unprecedented awareness in the target demographic; many women who had never previously done so had mammograms. It was bad because it also raised unprecedented awareness in young women, who exposed themselves unnecessarily to the risk of radiation and to the potential of false-positive results.
It's an example of how having a celebrity figurehead for a public health message can produce mixed results, says Simon Chapman, professor and director of research at Sydney University's School of Public Health.
Whether or not celebrities should be used to endorse such campaigns is a point Chapman debated in the British Medical Journal last week, with Geof Rayner, honorary research fellow at London University.
"Celebrities often get involved because of personal experience with a disease or because they share the concerns of other citizens and want to help by offering the publicity magnet intrinsic to their celebrity," Chapman wrote. "And like experts, some probably calculate that a public profile on good causes might also be good for their careers."
Ulterior motives aside, the ability for celebrities to bring an issue into the spotlight is second to none, Chapman says.
He cites the infamous Nicorette campaign with Shane Warne. "When he took money to quit smoking ... there were opportunist mutterings," Chapman told Life&Style. "I took the view that it gave quitting smoking legs that it mightn't have had otherwise... When he failed, people said he took the money and ran, but most people do fail [when trying to quit], often repeatedly. He might be a world-class cricketer, but he's an ordinary smoker."
The point is that his failure made Warne more relatable, more human. And this, in turn, may have inadvertently made the campaign more effective.
But for all their clout, celebrities can also affect a campaign's credibility. Chapman recalls when Nicole Kidman was supporting breast cancer awareness and was caught smoking a cigarette. "It sends a confused message - what, that breast cancer is a problem, but lung cancer is not?"
On the same note, he says we cannot expect celebrities to "be pure as the driven snow", as we so often do, because "frankly that's not true of experts either".
A part of the reason we come down so hard on celebrities, when we see any behaviour contrary to the campaign message, is because they are often paid.
"The subtext [of such concerns] is 'how authentic is it?'," Chapman said. "When you hear someone does something for money the tendency is to see their authenticity as diminished. But, we don't expect experts to do [campaigns] for charity - sometimes they are rewarded quite handsomely. It's quite a peculiar criticism."
Mike Daube, professor of health policy at Curtin University and director of the Public Health Advocacy Institute, notes that such paradoxes are rarely seen to be as problematic in the commercial sphere. He notes how many sports stars who are held up as images of healthy lifestyle are sponsored by booze companies. A moment that highlights the irony, he said, was when Australia's then cricket captain, Ricky Ponting, wearing a VB sponsored cap, sent fellow teammate Andrew Symonds home for drinking on tour.
"Commercial manufacturers such as those for tobacco, alcohol and junk food are only too keen to use celebrities in their promotional activities," he said. "They have done the market research, as have those of us who have at times involved popular figures in our health campaigns. Why should the devil have all the best celebrities?"
While Daube says the process of choosing a celebrity "should be done carefully ... and is sometimes appropriate and sometimes not", whether we like it or not, we respond to celebrity.
But Geoff Rayner doesn't believe celebrities are right for delivering important health messages. "It's not until you start delving into the role of celebrity culture on health that the negatives begin to stack up," he said. "What celebrity culture does so effectively is promote icons of rampant consumerism and fantasy lifestyle ... Not so long ago one celebrity entertainer, Ronald Reagan, told people what cigarettes to smoke."
Rayner acknowledges that "some celebrities might help [promote a good cause]", but he points out that celebrity status is often fleeting and therefore companies are unlikely to get bang for their buck in the long term.
He believes a better alternative is to "go on the offensive against junk food, alcohol, gambling, and other often celebrity-linked, commercial propaganda".
Celebrities can do good and bad to a cause, but what they do - or any other controversial campaign choice does - is put the desired cause on the map. The effect they have on important issues is more than "us mere mortals can struggle to achieve", Chapman says.
For better or for worse, this is precisely the point of such operations. As they say in showbiz, any publicity is good publicity.