oh i never touch em once that sign goes up not since i did one who asked me to call back for payment only to find they had moved the next day
Nooooo!
If a someone has been a faithfull customer for a number of months or years, the time when they come to sell their property is when they WANT you the most. They want their property looking smart for the potential buyers to view and it would be unfair to let them down at this point.
Okay, so you've been ripped off once in the past; so what? Don't think that everyone's as devious; they're not; and to be honest, maybe that customer who moved and didn't pay was just too wrapped up in the move to think about 'trivial' stuff like window cleaning.
Mind you, I've been caught out a couple of times where someone has asked for a quote from me, accepted, then I've cleaned 10 years worth of filfth from their windows, only to find a 'for sale' sign there on my next visit. That winds me up.
Houses with 'for sale' signs already up that want me to quote; I just ask a high price! I don't think one has been accepted yet, but I don't really care.