Done quite a few that haven't been cleaned for many a year.
It does go to show you that many people can live without their windows being regularly cleaned, however on the other foot, we regularly get people and particularly lately with the bad weather, who will phone us up on the day after the 4 week date when they were due asking why they haven't been done!
Er, sorry but we could hardly get out the house for 2 weeks! I am hoping to be caught up by the middle of next week if the weather holds off.