This week's tip is from Mustang Window Tint
When the customer arrives to pick up the vehicle go over the warranty and point out any cloudy areas that haven't cured yet and tell em it won't fully cure for thirty days. Collect payment and thank them kindly with a handshake and send them on their way.
"Get 'em in, make the sale, do the work, give them a thorough delivery devoid of b.s/smalltalk and get 'em out!" You'll save yourself a ton of headache this way.
After thirty days there is less than a 5% chance that they'll come back to bitch. No matter how good a job you do you'll always get the one guy who finds a single speck of dust on a HUGE back glass.
It's the same guy who fails to realize that you scrubbed, scraped and cleaned 300 other hard to remove specks just like the one he found just to get the job as clean as it turned out. This approach seems to work best for me.