I don't think the 3 clean rule is a con. I think its just a disclaimer to cover our arses.
I agree that time should be spent on first cleans and attention to detail is vital. But sometimes you could spend a long time on them and they won't be 100%
The odd spot, spec or run may still be visible. There are many variables why this may happen but it should only be minimal.
it can take 1, 2, 3 or even 4 cleans on some windows to get them perfect. not on many but it can happen.
I always say to the guys that we only get 1 chance to impress them and the first cleans are really important in building the relationship.
I think the 3 month rule is good because if there not expecting them to be 100% and you achieve that with 90% of new customers then they'll think your great!
![Wink ;)](http://www.cleanitup.co.uk/smf/Smileys/classic/wink.gif)