Linda,
I have started cleaning the FRONTS of the blinds with my hat brush.
I got this brush to dust my felt "cowgal" hat, in a western store.
Brushes rather short, handle sorta long (Like 5 inches or so??), paddle about 4 inches by 2 inches. (guestimates)
It might reach up behind there, I have not tried it. I will try to remember to check it out next time I am out there. I can see that I could get the backs when the shades are up, but there is no way my arm and that brush are long enough to reach from the bottom to the top on some of my windows. Not sure bout trying from the sides. Have to contemplate that all some more.
It does work quite well on the fronts, as it is not a stiff bristle, and if I go gentle, specially around those "cords", it gets them looking better.