On the face of it, as a society, we seem to be a little mixed-up when it comes to "graffiti", as you call it if you work in the local council's cleansing department, or "street art" as you say if you're the chap – and they do mainly seem to be blokes – wielding the spray can.
But the confusion now runs deeper than those who spray and those who remove the paint. Great British institutions have been polarised. Last week the might of English law delivered its verdict at Southwark Crown Court where five members of the DPM graffiti crew were jailed – one, Andrew Gillman, for two years – after admitting conspiracy to cause criminal damage costing the taxpayer at least £1m.
By contrast, just down the road, the riverside facade of Tate Modern had been covered in giant murals by six urban artists with international reputations, including Blu from Bologna, Faile from New York, and Sixeart from Barcelona, in the first display of street art at a major museum.
The courtroom and the museum were so close that supporters of the men on trial popped down to the Tate to do a bit of retouching during one lunchtime adjournment. "There is a huge irony in the juxtaposition of the two events," said one of the artists.
The man to credit for bringing street art into established gallery spaces is Banksy. A few years ago he was sneaking his work into galleries such as the Louvre and Tate Britain. Now Tate Modern is selling his book in its gift shop. His works go for hundreds of thousands of pounds and he was recently featured in a retrospective exhibition alongside Andy Warhol. He, more than anyone else, has legitimised the genre and spawned a new generation of young imitators – much to the chagrin of those who want to clean up behind them.
Bob has been involved in graffiti since 1982 when he was a punk. He now works, by day, for a London art gallery and describes himself as an upstanding taxpayer. "London is to street art, at the start of the 21st century, what Paris was for Impressionism at the start of the 20th," he says with unfeigned immodesty. "And yet we hate graffiti more than anywhere else in the world. England is by far and away the most draconian for punishments for what are only economic crimes."
A gallery in New York launches an exhibition next week based on the work of those convicted at Southwark. "DPM – Exhibit A", at the Anonymous Gallery Project in SoHo, will display large photographs of the convicts' work alongside copies of their charge sheets to ask whether the men are criminals or artists.
It is a question which prompts different answers in different parts of the world, says Cedar Lewinsohn, the curator of the exhibition at Tate Modern. "Brazil for instance is more relaxed about it," he says. "In parts of Australia, they are like the UK and people really hate graffiti and tags on vans and trains, but in Melbourne van drivers compete with each other as to whose is more decorated."
They have similarly schizophrenic responses in other nations too. In Toronto, police have just hired a street artist to paint walls to help find the man who murdered her brother. Elsewhere in Canada, a court has ruled that, after a police crackdown on graffiti artists, a 28-year-old man is only allowed to venture into town if he is accompanied by his mother. One internet blogger wrote: "In their twenties and still vandalising other people's property – shouldn't they have moved on to drug dealing, or perhaps become real estate agents by that age?"
Street art, you see, is a highly polarising phenomenon. On the one hand there are those like the American artist Elura Emerald, who is also involved in next week's New York exhibition, who insist that "artists who paint on the street are merely expressing themselves, not hurting anyone" and should not be punished "but appreciated and celebrated". Then there are those like Judge Christopher Hardy who, in court in Southwark, described the activities of the DPM Crew as "a wholesale self-indulgent campaign to damage property on an industrial scale".
How is such a dichotomy to be resolved? How, The Independent asked the street artist Bob, can artistic expression be reconciled with the fear and loathing that graffiti inspires in many citizens who see it as a symbol of lawlessness and the deterioration of their neighbourhood? "Well, not by sending them to jail," he says.
Gedis Grudzinskas, whose son Ziggy, 25, was one of those jailed last week agrees. "Ziggy has been sent to prison for 18 months having pleaded guilty to a crime not involving violence, terrorism, knives or drugs but vandalising public property," he says.
Having said that, Bob concedes, "you can't let people run wild". "If there's a clash of rights obviously those of the owner of the wall take precedence over those of the person painting on it," he adds. "There's room for debate but jail sentences shouldn't be part of that. They should just have to do youth work, or clean up ugly tags."
Greenwich and Tower Hamlets councils agree. They commissioned Ziggy and another DPM member to lead summer workshops as street art tutors for young and vulnerable people. The two councils sent references to court vouching that the DPM men were "positive" and "inspirational" in working with "young people who aren't able to do reading or writing". But it was not enough to save them from prison.
Is artistic merit enough of an excuse? A hoary old "is it art?" debate is taking place on street art next month at Tate Modern. Under the title "Graffiti – Utopia or a bit boring?", two art critics will consider whether graffiti is "glorified vandalism or a legitimate cultural movement". Bob does not think it will help much.
"Street art starts with kids doing ugly tags," he says. "When a kid starts to play music only the next-door neighbours hear but with street art the whole neighbourhood sees him not being very good when he starts out." The trouble is there is a whole lot of learning going on.
Some 85 per cent of graffiti is just tags, and another 10 per cent is gang communication, according to US sociologists who survey this kind of thing. And who, anyway, says Bob, is going to police "what is art and what is ugly"?
The money men will not help much, for all their attempts to cash in on street art. Red Bull, Adidas, Puma, 55DSL and Lee Jeans have all incorporated graffiti into their marketing campaigns. The BBC hired the DPM Crew's ringleader Andrew Gillman to deface the set of EastEnders to add a sense of authenticity to Albert Square. And the German paint firm Belton has even developed a new line of spray paint called Molotov aimed at street stencillers, with colours named after well-known graffiti artists.
So if artistic merit and commercial value aren't yardsticks for resolving our national confusion what is?
"I suppose the greater the cost of removing the graffiti, the greater the punishment should be, though not prison," says Bob, somewhat unexpectedly. This is not a million miles from Judge Hardy's verdict on the two-year spree in which the DPM Crew staged 120 night-time attacks on stations, trains and railway rolling stock in London, Somerset, Liverpool, Manchester, Sunderland, Paris, Amsterdam and the Czech Republic.
The judge had little patience with Gillman's notion that "trains were like a moving canvas" on which to create something artistic and thought-provoking that made "commuters look up from their paper".
Judge Hardy admitted that "it would be wrong of me not to acknowledge that some examples of your handiwork show considerable artistic talent", but he concluded, "the trouble is that it is has been sprayed all over other people's property without their consent and that is simply vandalism." Over the two years the bill must have run into millions of pounds.
If art is defined by the artist's intent then vandalism must be determined by the response of the owner of the thing vandalised. Peterborough City Council recently tried to find a compromise. It erected two 8ft by 4ft boards to allow artists there to express themselves freely. The trouble was that they were pulled down by vandals.
Additional reporting by Kate Mead
Six of the best street artists (apart from Banksy)
Insect's Pop-art inspired street art has rapidly risen in profile. Last year, Damien Hirst snapped up his entire collection before it reached exhibition for a reported £50,000, while the actor Kevin Spacey has also acquired some pieces. Insect is best known for his anti-establishment messages.
One of the most respected and sought-after artists in Britain, Rough uses letterforms for his graffiti artwork. With a career spanning nearly two decades, Rough's work has been exhibited to critical acclaim in Australia and across Europe. A graphic designer, Rough has published a book, runs a T-shirt label and releases records as a rapper in a hip-hop band.
Blek Le Rat
The grand old man of street art is said to have paved the way for Banksy. After years of dodging the French authorities, he ended up being embraced by them. The Parisian has been spraying stencil-art graffiti since the early 1980s, the style favoured by Banksy.
Best known for the letters he paints on shop fronts around London. He spray-painted the word "nightmare" along a 110ft wall in an exhibition of street art in east London last year showing an alternative vision of Christmas.
Emerged from the 1980s Bristol graffiti scene alongside Banksy. His work Moona Lisa – a bottom-baring version of La Joconde – went for £54,000 at Bonhams.
Robert Del Naja
Also known as 3D, the street artist and musician was part of the Bristol collective known as The Wild Bunch and went on to become a founding member of Massive Attack. His first live gig was as a DJ accompanying artwork he had produced in a Bristol gallery.