So this one time I used a older toothbrush to clean my church shoes. Its annoying you know? All that little gunk that gets into the crevices of black shoes! Well anyways, I put it back in the bathroom.
they work great for getting small areas or for hard/greenspot algae... not so great for large areas... however they sell power brushes at homedepot for like $25 that have a 3/4" head on them... they are made for toilets..