We found exactly the same: Young families, new mortgage, 2 cars on finance, credit card bills. When I started I was given the same advice by a seasoned windy buddy as the gardening guy gave you.We have also found that customers on entry level new build estates aren't always the best long term customers. They sometimes over extend themselves financially and good intentions, such as clean windows, can be a dream which may not end up to be the reality. A local lad who does gardening services says the same - his advice to me was to stay away from entry level new build estates.
Amazingly though, these new estates are 'swamped' with window cleaners distributing leaflets offering their services. I haven't had one through our door for a long time now.