I heard or read a similar story about some schoolgirls who used to put on lipstick & then kiss the mirror in the toilet, leaving it covered with lipstick for the cleaner to remove. After several useless appeals to the girls, a teacher took them down to the toilet so that they could see just how much work it was for the cleaner. The cleaner had to dip the mop in the toilet bowl many, many times to get the lipstick first off the mirror onto the mop and then off the mop.
History does not record whether the girls stopped because of the hard work they caused or because of the source of the water for the mop. But they stopped!