State Board requires all tools to be cleaned after every client. If a client has any blood, this dry blood on a fluffy cosmetic brush could spread disease up to a week. Fluffy cosmetic brushes are porous. They harbor germs, oils and debris which can also cause dermatitis, nail allergies and infections. 

If you are using Fluffy Cosmetic Brushes, have at least 3. 1 that you're using on your client, 1 that is drying after you clean it, and 1 in your clean container for your next client. 

I prefer plastic manicure brushes over fluffy cosmetic brushes. Plastic manicure brushes are extremely easy to thoroughly disinfect. Just place your plastic manicure brush in your disinfect after every client.

Always remember to ask questions and do your research!