I remember one time at the Guggenhiem seeing an artist' exhibition, whose work was essentially giant photographs of old advertising posters and quotes printed across 10 foot canvasses. There was also a nude photograph of Brooke Shiels at 12. (child porn in another setting?)
The images were directly and obviously derived from other peoples work.
I am not sure how he got away with it. Mayby some boffin can explain it.