Was working to get a stain out of a lounge carpet in a rented flat when the joiner arrived to replace some plaster board on the wall.
I asked him what was wrong as it looked damp and we were trying to find out what caused the stain. He said the plaster had gone soft as the upper part of the body had been leaning against it for approx six weeks. Landlord had omitted to tell us what caused the stain on purpose as he thought he would be over charged for the cleaning.
He was right.
Cheers
George