People never like change, they've been indoctrinated as to what a 'proper' window cleaner is. Completely bypassing more important things, like professionalism, reliable, and regular. They get their windows cleaned, what's the big deal. AS long as they are nice and clean, I wouldn't mind how somebody would do it.
There are plenty of people who absolutely love it, and are very impressed, don't let those people get you down.