Tough times can sometimes force consumers to make rash decisions. So maybe it’s time to forget the Lipstick Index and turn to the Diaper Rash Index, as it appears that even indispensible disposable diapers aren’t recession-proof, according to a new study by Consumer Edge Research. The tight U.S. economy has turned even essential goods into luxuries. Now consumer-goods companies are seeing something they thought would never come to pass: Parents are buying fewer diapers. What does t...