I have 3 flats close together, all with older women living by themselves. One above another, and the top flat next door. One time, shortly after i started doing them, i had done the windows and moved along the street a bit, when the old guy in the downstairs flat that i don't do, came over and started moaning about the mess i had made of his windows. After pointing out that it was pure water, and actually cleaner than what he gets on his windows when it rains, i went back over and cleaned his windows, while he watched. I then told him that i was going to tell the old lady upstairs that i wouldn't be able to clean her windows again. He got all flustered and said not to bother, it was OK, just to carry on cleaning them, and has never mentioned it again!.