Thanks, i've tried loads of areas but they either look spotless or everyone works. Think the weekend might be a better time to knock. I'm wasting too much fuel. Funny thing is most of my work is right on my doorstep within a mile or two.
Rule no 1: Never assume anything, just because they are clean doesn't mean they have a window cleaner, they may have had to do the windows themselves as they can't find a window cleaner! They may have had them cleaned but are really unhappy with the current window cleaner and are looking to change?
Always look at the top windows and never the bottom windows as you approach a house as these are the ones they can't generally clean. The householder can easily whip round with a cloth for the downstairs.
Always knock and if they have a window cleaner politely leave your card and walk away (never try to poach or undercut), you may get a call in 6 months when you least expect it as their existing window cleaner has packed in or they aren't happy with him.
Always leave a card as sometimes they will refere you to a friend despite already having a window cleaner.
Put it this way, if you don't ask, you don't know and more to the point, they don't know about you!