Just because something's in the shower doesn't mean it stays clean. If you use one of those plastic mesh sponges to lather up when you shower, it needs to be periodically cleaned. Over time, the moisture buildup can create a breeding ground for harmful and smelly bacteria. To clean it, just toss it in the washing machine whenever you launder something that uses hot water. This will eradicate the bacteria and germs. When it's done washing, don't toss it in the dryer, just air-dry it.