The 2 things you need to do in order to avoid this.
1. Never call any package "Full Detail". This implies it is all inclusive and can mean many things to many people.
2. Older vehicle waiver. Any vehicle that is more than 5 years old, the customer has to sign a agreement before I touch their vehicle. This will include plastic discoloring, mechanical, headliner sag, and old paint failure. There is always a risk trying to clean these cars, the customer needs to understand that I will not be responsible for these worn parts.
Renny Doyal's book has a great example of this in the appendix.
In the end some people will never be satisfied. I had to "fire" one of these customers last year. After spending an hour trying to fix all the little things he kept pointing out, I just gave him half his money back and told him to call someone else next time.
Sometimes I filter potential problem customers out over the phone. When they start to tell me about all the bad detailers they have been thru, it's a huge flashing sign for me.
Bottom line is you don't need to take every job, if I get a bad feeling talking to them on the phone I will let them know I may not be the guy your looking for and I give them the number to my closest competitor. Let them deal with that headache.
Macomb Dents & Details: Car Detailing and Paintless Dent Removal
www.Facebook.com/DentsAndDetails
I may be slow, but I do poor work.