Somewhere in the backs of our minds, we know that it’s not a good idea to apply the same tube of lipstick that countless others have been trying – yet we do it anyway for the sake of convenience when we’re out sampling makeup at the department store.

According to Allure.com, however, women should really think twice, especially after talking to former professor Elizabeth Yesuratnam Brooks, who performed a study on makeup tester germs. “More than half of all testers were contaminated, and we found staph, strep, and E. coli bacteria from feces,” she told the news source, effectively explaining that “you can contract pink eye, infections, or even viruses like herpes or hepatitis” just by swiping on a shadow.

Fortunately, most makeup counters will clean off samples for you, but Allure advises that you stay away from products that come in a pot, since there’s no way to clean the entire product, and to stay away from your eyes and lips if you’re not sure your sample is totally clean.

Another way to avoid too much exposure to potentially harmful testers is to pay attention to which color families generally work for you. When you know what you look good in, you won’t need to think twice (or dabble in anyone else’s germs).