If I had all the customers that I wanted or needed I would charge extra for a first clean.
Yesterday morning a lady asked me if I cleaned in her road. I went there in the afternoon and quoted for her detached bungalow. I could see the frames were pretty clean, she accepted my quote, she said the next door neighbour wanted a quote too so I went there and he accepted my quote. His frames were not bad. I walked back to he 1st one and she had changed her mind and only wanted the front doing. Did that and next door and then the one next to that wanted his done, they were filthy but I did not charge extra. It probably only took me 5 minutes longer, he was pleased and said next door was looking for a window cleaner too.