Dry, Dirty Sidewalks

I realize that the rainy season does not beging here in SF until about the end of October but we need a good hard steady rain now. Our sidewalks are so filthy with black stuff, brown stuff (better not step on that) and other gunk that after walking around some sections of the city for awhile I feel like I should sterlize my shoes before wearing them into the apartment. I admire the business people who will either steam clean their sidewalks or at least hose them down on a regular basis but too many do nothing and the filth builds up to unbearable amounts. Maybe there should be some sort of fine imposed on those laggardly people equal to the amount of what a company would charge to steam clean the sidewalks. That would probably end that problem fairly fast.