Hair brushes are actually pretty easy to clean! Clear out the hair with a comb, a rattail, and/or scissors, and then soak any gunk off of the bristles with a mixture of warm water and dish soap or shampoo. I usually let it sit for ~15 minutes and then scrub it a little against my hand, rinse it out, then let it dry completely before using it again. There are lots of tutorials on YouTube with tips for cushion-type brushes or natural fiber, &c.