When he first appeared on TV in the mid-70s, he was a skinny, spotty, sneery youth with spiky ginger hair. He was a last-minute stand-in on the bland topical tea-time show, presented by Bill Grundy. Asked his opinion of Mozart and Beethoven, the young man mumbled ‘a rude word’. Goaded by Grundy, he repeated the word out loud. It rhymed with ‘hit’.

It’s possible Grundy was drunk. The middle-aged TV host then flirted mildly with one of the young women present – who in years to come would turn out to be Siouxsie Sioux of The Banshees. The show ended in chaos with the prickly young interviewees calling the host ‘a dirty b*****d and ‘a f*****g rotter’. The incident killed Grundy’s career, just as surely as it kickstarted the band’s.

The last time I saw John Lydon on TV – aka Jonny Rotten of the Sex Pistols – he was wearing a loud tartan suit. He wasn’t among the celebrity endorsements for the Yes Scotland campaign though. As the man who made Anarchy in the UK famous that might not have been so strange. Most bizarrely, the one-time arch-punk was fronting a TV ad for Country Life butter.

Now, incongruity is a powerful force in communications. It forces us to pay attention. From pre-history, our underlying physiology has been tuned to alert us to potential danger in our environment. You can safely ignore anything you’ve seen before, anything to which you’ve become habituated – like today’s ticking clock or the hum of distant traffic. But anything ‘novel’ that happens, anything unusual or unpredictable, you notice. Even if it’s just an aging punk rocker acting up rather than a sabre-tooth tiger sneaking up.

So, simply disrupting an audience’s expectations can be a big attention-grabber: an urban rebel in a traditional rural setting; a gorilla with a drumkit; a meerkat in a smoking jacket. That’s easier said than done though. Brands often like to align the stars in their marketing plans, and risk-manage the message. But, by taking out the unexpected, they create predictable ads and let people screen out the communication.

Not surprisingly, according to the marketing trades, Jonny’s campaign for Country Life wasn’t rotten at all. Following the campaign, the client reported an 85% uplift in profits.

Yet celebrity endorsement doesn’t always turn out so well. The first star to cash in on his status was comedian Fatty Arbuckle. He became the spokesman for a brand of cigarettes, offering his fans ‘conclusive proof that Murad has become the natural preference of men of cultivated taste’. By 1921, he had become a star of the silent screen and got weighed in to the tune of $1 million by Paramount – more money than any Hollywood actor had ever been offered.

Famed for the lightness of his footwork, Arbuckle should have been dancing all the way to the bank. Except fate had a pie-in-the-face waiting for him.

At a party to celebrate his success, a young actress took ill. Virginia Rappe died three days later in hospital. With rumours swirling around Fatty Arbuckle’s involvement, he was charged with manslaughter. After three trials lasting 15 months, Arbuckle was eventually acquitted but it was The End for his film career.

That’s the key concern for clients with celebrity endorsements. Will their famous friend behave badly and suck their brand into a maelstrom of bad press?

For nearly 20 years, athlete-turned-actor-turned-murderer OJ Simpson put ‘the superstar in rent-a-car’ for Hertz. (The white Ford Bronco in which he made his infamous slow speed getaway belonged to a friend rather than Hertz.) The story of actress Natalie Wood’s drowning re-surfaced recently and called into question Robert Wagner’s endorsements for a US finance firm. With the case re-opened, the police say he’s not a suspect – but would you buy a reverse mortgage from this man?

Besides death, there’s sex and drugs. Look what happened to Tiger Woods, Ryan Giggs and Wayne Rooney. Brands rush to distance themselves from such fallen idols. Or, as in the case of Kate Moss and her cocaine use, she was chucked by Chanel, H&M, Burberry and Rimmel. But Dior stuck by her and Virgin Mobile and Topshop slunk in. After all, she’s only a super-model not a role-model, right?

Sometimes though, celebrities just won’t play ball. Like Beckham, they might take many millions to promote, say, the ‘Brylcreem Bounce’, then shave their head.

It’s no wonder brands often take out ‘death and disgrace’ policies to insure themselves against celebrity marketing malfunctions.

But bad behaviour isn’t what bothers the public about star endorsements. According to market research group Ipsos MORI, only about 25% of us say we would boycott a brand if its celebrity endorser behaves badly. But only about one in ten will actually follow through and stop buying.

In the UK, part of the problem is that we’re used to ‘honest’ marketing. Our semi-voluntary, semi-regulated system maintains that all advertising must be ‘legal, decent, honest and truthful’. So, celebrity endorsers must provide signed evidence that any statements are their own truthful opinions. Despite our own tawdry celebrity culture, celebrity ads are reasonably rare and we tend to take the famous at face value.

Of course, we all know that Gary Lineker lives on nothing but potato crisps. Over in the USA, consumers are not so lucky: about one in five American ads feature a celebrity. And you might be surprised who has sold out.

From his early days as a sportscaster ‘Dutch’ Reagan posed for tobacco, pipe in hand. When he became a leading ham in Hollywood, he switched brands to Chesterfield cigarettes, maintaining that these ‘mild’ smokes were the ideal festive gift for all your friends. By the time Ronald Reagan was President of the USA and the leading man in the free world in the 1980s, jelly beans were his new addiction – along with right-wing hokum. From the ‘Reaganomics’ which he must have given Mrs Thatcher in a cracker one Christmas to the Iran-Contra arms scandal, it wasn’t obvious that Ronnie even knew what the truth was.

There are only two real problems that the public have with celebrity endorsements. The first is credibility. Does the subject have any credentials for talking about this product? What exactly made DJ Jimmy Saville such an authority on ‘the age of the train’ and the government’s ‘Clunk Click’ car seat belt campaign?

The second problem also revolves around credibility. It’s not just the money: it’s the pursuit of money. So, the more endorsements a celebrity takes on, the less their endorsement is worth. So when George Clooney advertises a coffee-maker, a watch, a bank, a car, a beer, a vermouth… he merely looks like a man for hire.

Only in politics does the cash flow in the opposite direction. Clooney also endorses Obama and recently ran a fund-raiser for the President. You could win an online draw to have dinner with the real gorgeous George or pay £30,000 for a ticket. The event is said to have raised around £10 million.

Indeed, it seems likely that celebrity cash may be more important than their kudos. Experiments by University of Tennessee professor Anthony Nownes suggests that, when the famous endorse politicians, it may change attitudes to the party – but not voting intentions.

The question of Scottish ‘celebrities’ and their likely impact on the Yes Scotland campaign remains moot. It hardly inspires confidence when this paper had to give readers a key to the photograph – so they could tell who the celebrities were.

Perhaps the saving grace for the Yes Scotland group was that they did have Scotland’s most recognisable figure on the platform. The First Minister himself remains the only personality in the picture that matters. Maybe, just maybe, all Salmond really needs to succeed is a loud tartan suit like Jonny Rotten’s.


A version of this article has previously appeared in ‘The Scotsman’