After they had checked out, I got a report from the cleaning company I was using at the time that all the hand towels we had put out for that group were missing. Because I had spent so much time on the phone with members of this group, I decided to just phone them and ask if they had the hand towels, instead of immediately assuming that they were lost and deducting it from their deposit. After a pause, my guest responded to my question with an "Oh! We washed them all and forgot to unload them from the dryer."
I remember this every time I'm tempted to assume the worst about people.