One of our sellers several months ago unhooked their washer and dryer and did not cap off their water connection (a simple inexpensive part at Home Depot). You guessed it - water dripped down the wall and drywall needed to be cut out, replaced hours before closing.
I mentioned this occurance to a seller recently as they just moved out and asked them if they capped their water connection from the washing machine. She was still in the house cleaning and walked over into the utility room and guess what...the same thing happened! Luckily we were able to get a contractor over that afternoon repair the sheet rock, texture and paint for their closing the next day.
Yesterday I talked with a seller who is moving out next week and told them to make sure they cap off the water connection and their refrigerator connection when the appliances are moved. I've decided this information needs to be explained to each seller before closing, so there are no repeats of this incidence! My seller already thanked me for the heads up as she did not know this could be an issue.