Mark Steel: However debased the image, Che's legend lives on

The image of Che Guevara is perfect for the modern world, not just a revolutionary but a celebrity revolutionary. Posh Spice probably sees his picture everywhere and screams "Why can't my agent get me on that many magazines and baseball caps?" Even if she's read this week's commemorations of his death as a guerilla 40 years ago, she'll imagine he spent his days running through a Cuban swamp with Churchill Insurance on his combat fatigues.

Or that he often stopped to film an advert in which he says "Hi, I'm Che Guevara, the world's most famous guerilla. But you know, when I'm trying to fire on government agents the last thing I need is to lose concentration by worrying about my split ends. That's why I use new Clairol Herbal Essence conditioner, to give my hair extra bounce, and my ambush extra pounce."

It clearly didn't do Che's brand any harm to be a revolutionary who countered most images of the revolutionary. So his account of his road trip, The Motorcycle Diaries, was reviewed in Bike News as "Six months of high drama in which the main concerns of Che are where the next drink is coming from, where the next bed is and who might share it."

Apart from anything else, this is probably the only book by a revolutionary to be reviewed at all in Bike News – unless there's one of Marx's The Communist Manifesto that goes: "Very disappointing. Hardly mentions bikes at all." Or another of Mao's Little Red Book that starts: "Why go on that long march when a Kawasaki 850 would have got him there in two days at the most?"

But also, no matter how debased his image, and how many watches and bars and cocktails and shirts he appears on, even if people don't know much about him, they're aware he was a little bit naughty. Through 40 years of posthumous commercialism, he's somehow survived as a rebel. And that's probably reasonable, seeing as how he helped to overthrow the old government in Cuba, became head of the bank, but then left in disguise to go to the Congo and then Bolivia to start all over again.

The CIA compiled a report on him that said: "Che is fairly intellectual for a Latino." And in a further attempt to get a job as a phone-in host on TalkSPORT they added "Unusually for a Latino, he doesn't submit to their native rhythms." So it's possible the CIA reports were being written by a bloke in a pub in Kent. And it went on: "And you've got to watch yer Mexicans, wearing them tablecloths and screaming 'Yrrrrrr yahaha yeehaaah' and firing guns everywhere. Mind you, I'd still take them over the French."

It would seem that Che's most obvious legacy is in Cuba, where the government he helped set up survives, in spite of US blockades, countless farcical assassination attempts on Castro and still being on George Bush's list of countries sponsoring terrorism. And the regime it replaced was run by gangsters, in which one-third of all public payments went directly to the corrupt President.

But this is where the idolisation of Che becomes a problem. Because for many people this image is part of a Cuba that's all it claims to be, a socialist beacon of equality and justice that doesn't fit the reality. Because much of the workforce has no choice but to work for dire wages, many of them servicing foreign companies or tourists, but any attempts to organise trade unions or opposition movements are stamped on.

Within this atmosphere of no dissent, Che is almost treated as a messiah by the Cuban authorities and their supporters, and you can no more suggest he was flawed than you could shout in church during a sermon about Jesus: "I bet he didn't kiss Judas – he just thought 'I've ballsed this situation right up'."

I came across a tiny version of this deification of Che, courtesy of a cosy cafe in my area, in which the walls are covered with Che pictures. So one morning I went in for a cup of tea, and was told "GET OUT", because the owner had heard a radio programme I'd done, which was mildly critical of her hero, and I've been banned ever since. The strange thing is I admire her for this, and I'll be quite disappointed if she ever lets me back in.

The real Che was clearly flawed, because when your plan to overthrow a government ends in a group of 11 hiding in a hill with no support and getting shot, that suggests things haven't gone entirely to plan. And the Cuba he helped to create is flawed. But his main legacy is to leave behind a symbol of opposition.

And there can never have been a politician less on the make. When some students invited him to speak at their college, offering him a fee, he went berserk, saying he could never accept money for what he saw as part of his duty. Maybe a few years later the same college tried to get Cherie Blair, and she went similarly berserk, screaming "Only 20 grand? Don't you know who I am?"

So although millions of companies have used his image, it's always in an attempt to appear on the side of spirit and rebellion. It still signifies something. So it can be worn by millions, including many who probably disagree with most of his ideas, but it's never been more popular in South America, and you're unlikely to see it worn by Margaret Beckett or Donald Rumsfeld or Noel Edmonds. And even if Gordon Brown had piercing blue eyes and a Marlon Brando laconic smile, in 40 years no student would put up his poster and say: "His vision for the future, man, it was, well, cool."