We charge double on all first cleans.
we quote over the phone so we don't know the state of the windows.
your first clean is a deep clean, it takes longer and uses more water so we charge double.
most people don't seem to worry about it, some don't like it. we get about 60-65% of telephone quotes.
those we miss aren't only because of the double first clean. i think the majority of people who are happy with the reg price, happy to pay by DD etc are happy to pay double