Since other products are present on the bristles, they don’t apply foundation or other products as smooth as they normally would. Not only do dirty makeup brushes cause skin problems, but they also make your makeup look streaky. When you use the spreading action on your face with these brushes, you’re distributing acne-causing bacteria all over your face. You may not see the brush becoming dirty, but the bacteria are there, and they will eventually cause acne and breakouts. Makeup brushes can quickly become a place for bacteria to thrive in. It is even more dangerous for your skin if more than one person is using the same brush. This is why a dirty brush does more damage to your skin in the long run than making it pretty. This accumulated gunk makes the pores on your skin clogged up, causing whiteheads and much more. So every time you sweep those bristles across your face, some oil and dead skin cells accumulate on them. Your skin has oils present on it known as sebum.
