UPDATE (Backdate?): One of the commenters was reminded of something that had crossed my mind too: that time a janitor threw out a trash bag that was actually part of an art exhibit:
A bag of rubbish that was part of a Tate Britain work of art has been accidentally thrown away by a cleaner.
The bag filled with discarded paper and cardboard was part of a work by Gustav Metzger, said to demonstrate the "finite existence" of art....
The bag was part of Metzger's Recreation of First Public Demonstration of Auto-Destructive Art, a copy of a piece he produced in 1960...
Metzger, a German artist who lives in east London, invented "auto-destructive" art in 1959.
The work also features an "acid painting" - nylon covered in acid which slowly destroys it to illustrate the transient nature of paintings, sculptures and other artworks....
It is not the first time such a mistake has been made. In 2001 a cleaner at a London's Eyestorm Gallery gallery cleared away an installation by artist Damien Hirst, having mistaken it for a pile of rubbish.
The collection of beer bottles, coffee cups and overflowing ashtrays was said to represent the chaos of an artist's studio.
And in the 1980s the work of Joseph Beuys, which featured a very dirty bath, was scrubbed clean by a gallery worker in Germany.
I can't help suspecting that these are, if not deliberate publicity stunts, hoped for or welcomed opportunities for press coverage.