Have you ever been to a party where the bathroom hand towel has been used so much it's become a smelly, moist wad? As a host you should offer a cleaner option, not just because that towel is gross, but because it's loaded with germs.
Hand towels are actually a great home for germs. They're usually pretty thick and hang in a moist location, meaning they take a long time to dry out. They also contain skin cells, which the germs can use as fuel. That means a few bacteria deposited on a towel can quickly multiply, leaving you at risk of picking up more each time you dry your hands [source: Braff].
To avoid turning your hand towel into a science experiment, wash it every three or four days using hot water and bleach when possible. If you are having a few guests over, set out a clean towel before they arrive. A larger party may require you to ditch the reusable towels altogether and opt for disposable ones instead — decorative sets are available at many bed and bath stores.