I cleaned an house, and happened to notice I left a lot of brush marks on the downstairs. That puzzled me somewhat as they usually come up fine, did one again and no improvement. Investigated the house and found some ice cube tubs filled with dripping on a water butt, so figured I'd somehow picked up some of that on the brush, so squirted jif on them and did them again, and again and a good rinse, fine! Can't for the life of me figure out why the drippings there, something to do with birds I guess?