 Swimsuit liners don't do what you think. That thin layer of plastic isn't protecting you. Experts say they aren't really a safeguard against bacteria or viruses in swimsuits, while they tend to carry fecal matter, yeast, and other germs that can make you really sick. So next time you're trying on swimsuits, try this. Wear protection. Keep your underwear on, and make sure to wash them when you get home. Wash your hands. Organisms can survive months on you clothes. Do yourself a favor and wash off any potential fecal matter you may have accidentally touched. Wash it. Never wear a swimsuit that hasn't been washed first. This goes for men's trunks too.