British graffiti artist Banksy's month-long 'residency' on the streets of New York has already produced some witty, surprising and thoughtful artworks - but almost all of the pieces have been defaced.
A stencil of a heart-shaped balloon, covered in plasters, was designed to show the struggle to mend a broken heart. But now the piece, on a Brooklyn wall, sports an "Omar NYC" tag.
People booed the vandal – who apparently has a history of adding his tag to Banksy pieces – as he ruined the work, according to the New York Post.
One Banksy piece, showing a dog urinating on a fire hydrant, is now covered in artless graffiti. Another, in which the artist proclaims, "This is my New York accent", is now indiscernible from a melee of tags.
In addition, a long-time Banksy admirer claims to have unmasked the anonymous artist.
Thomas McKean, 26, said he spotted Banksy as he was preparing one of his unusual pieces: a delivery truck that acts as a mobile garden oasis.
He asked one of two men in overalls whether he was Banksy, and the individual responded: "No man, I'm a truck driver."
In 2008, it was claimed that Banksy was actually Robin Gunningham, a former public schoolboy from Bristol. The artist denied the claim.
Despite the dangers of painting the streets - the criminality, the risk of being identified, the regular frustration of having your work defaced or painted over - the artist isn't about to go back to the cosy and profitable world of the gallery.
"I started painting on the street because it was the only venue that would give me a show," Banksy told Village Voice.
"Now I have to keep painting on the street to prove to myself it wasn't a cynical plan. Commercial success is a mark of failure for a graffiti artist. We're not supposed to be embraced in that way."