When we bought our house, the neighbors were an older couple, retired Brown University professors...as eccentric as can be. The gave their two dogs (retrievers) the run of the house but never let them out. The only place they were allowed to pee was anywhere in the basement.
The couple defaulted on the mortgage and was evicted a few months after we moved in. A contractor bought the house and spent two years completely stripping down and redoing everything so he could sell it. He did. That was ten years ago and there's been four different families buy it since then. They never last more than a year because they can't get rid of the urine smell.
They've all tried. One brought in a fire damage restoration company because they specialized in getting rid of smoke smells. Another had the entire basement coated in a rubberized paint to seal the smell. Another family had all the interior wood in the house replaced...floors, doorways, stair railings. Nothing helps.
On a hot summer day, if the wind is right, I can still get a faint whiff ten years later. And dog urine is nowhere near as noxious as cat urine. My guess is it will remain a part of Grey Gardens forever.
Art has a double face, of expression and illusion.