Not observed, but the last time I had to take a test I got a little on the back of the toilet and I didn't wipe it up because my thought process was, "They're so picky about what you can and can't do in here maybe I'd better leave it? I don't have more piss to give if they take issue with it..."

The lady in charge immediately came and saw it and wiped it up and then I saw the sign saying, "Please wipe the toilet when you finish." Sorry lady.