[oh_sigh]

Can I not sell a photo of a new York City street scene if one of banksys pieces is visible in the background?

[krsdcbl]

That really depends on what the picture represents in the end: how you describe it, yes. If you just take a front-up shot of the graffiti only then it would be hard to argue that you were depicting the city/scenery and not trying to reproduce the art.