I am an experienced driver with over several thousand trips. One of my friends fell for the cleaning fee scam recently. I have shared this in the past on this forum, but I would like to again warn people that cleaning fee scam is real and some drivers just pour a bottle of water and then call it is pee. You can't tell the difference in a photo.
After taking a pic, they just wait for it to try, and voila, the stain is gone.