She's not a good customer if his work is normally 2 monthly. She won't be an anything customer in 6 months anyway. A leopard doesn't change its spots. I do hope Dave charged well for that.
I beg to differ!
One of my first customers had absolutely black windows and frames. I wish I had a camera phone at the time. They were that dirty, that I couldn't shift the grime, scrubbing normally with an applicator sleeve. You literally would need to have the lights on in the house all the time the windows were that black.
Still cleaning her windows on a regular monthly basis to this day, after nearly 11 years.