When you get a nasty stain on your clothes from food or grease, you probably spot-treat it with detergent and toss it into the washing machine. Sometimes it works, but often it doesn't. The reason? The laundry detergent needs time to penetrate the stain and break it up. Next time, spot-treat the stain and rub in the detergent, letting it sit for 15 minutes. Then wash your garment. It should be spot-free.