You would be surprised how many window cleaning companies are actually doing very well.  With our lead generation services we speak and work with lots of window cleaners.  I work with at least 3 window cleaners that are doing £1 mill+ a year.  2 of which have 18 vans on the road, plus plenty of companies we work with have 5+ vans and are rapidly expanding year on year.  So lots doing 400-500k+ a year.
then you have franchises.  I know of at least 4 franchises right now in the UK for window cleaning that are doing well over £1 mill a year, one that has 30+ vans on the road.  Franchises seem to be expanding at an alarming rate.  We work with a few franchise companies, but most of them are trying to do everything in house now right across the board.
Things are definitely ramping up in the window cleaning world i would say.