I hate washing my makeup brushes.
Which is one of the reasons that I own about 50 of them. I will do anything to get out of washing them and at the same time avoid using one that's not clean. So the other day when I was about to buy a new brush I bought a brushed instead - Amazon Prime will be the end of me.
Washing your brushes is very important because bacteria grows in your brushes and make up sponges like no tomorrow. If you don't wash brush and then add more product to that brush then put it back onto your face, you are just ruining your skin by smearing this mix of makeup and bacteria all over it.