I actually have my own quality control system. Its a questionnaire that asks basically what you said John. I've left out the questions you've posed already.
Please excuse the caps, but I pasted them straight from my sheets. I keep these as testimonials in a hardback A4 folder, along with photo's of my awning cleans.
PLEASE TAKE YOUR TIME TO FILL OUT THIS FORM, SO I CAN IMPROVE MY SERVICE
WERE YOU REFERRED BY ONE OF MY EXISTING CLIENTS? IF SO,WHO?
WOULD YOU RECOMMEND ME TO ANYONE?
DO YOU THINK THE PRICE IS FAIR, FOR THE SERVICE OFFERED?
HOW DID YOU HEAR ABOUT MY SERVICE?
"DID YOU KNOW THAT USING AN UN-INSURED/ILLEGAL WINDOW CLEANER, MAKES YOU THE EMPLOYER, LIABLE FOR ALL ACCIDENTS & THIRD PARTY LIABILITY?"
"HAVE YOU HEARD ABOUT MY PURE WATER TECHNOLOGY?"
"HOW DO YOU RATE THIS CLEAN COMPARED TO OTHER WINDOW CLEANERS?"
"ALL THINGS CONSIDERED, HOW SATISFIED ARE YOU WITH THE WINDOW CLEANING SERVICE PROVIDED? VERY SATISFIED SATISFIED DISSATISFIED VERY DISSATISFIED"
With COMMENTS & SUGGESTIONS.
One big winner lately is using the slip on plastic shoe covers when cleaning windows inside the house.