I probably buy 1-2 every year, and "retire" the old ones to wheels and under-sills. I honestly have 20 in my garage, on nailhooks. Low hangers are for wheels and underside. I have never-ever washed one. They pick up brake dust just as well old and filthy-black as they did when new...
Have you ever seen the totally BARREL-ROUND ones? LARGE and MOPPY ! Truck Dusters or some such...$25. The BEST! I had a black customized StealthTT [MoPar Performance News Sept '91]and CA dusters saved my sanity.....
Best thing besides Zaino.