The Viennese artist Gustav Klimt (1862-1918) was an elegant man who loved life, women, coffee full of whipped cream -- and cats. He let his have free run of his studio, and there were plenty of them. A story relates that a friend showed up to visit, and asked why he let the cats do whatever they pleased, especially since it made the place smell!
This was Klimt's answer: he didn't mind, and if they peed on the pencil drawings, "that's the best fixative!" (That is, a product that "fixes" and finishes a drawing surface so that it won't smear.)