[Guelster]

If you dont have the customer sign a waiver, authorizing you to perform work on their vehicle you can easily get a headache.
An irate customer who wasnt at all satisfied with your work can cause a world of trouble. I know they are few & far between but people know how to get around the law, some people are just out there to work the law & get stuff for free.
Example: if a customer pulls up to your location and inquires about getting a broken windshield fixed..you agree on a price and start performing your repair. If the customer starts complaining ...they can still see a mark....they thought it was going to come out spotless....bla, bla, bla...they can say anything. I understand some of you will say you completely informed the customer on how it would look & you covered all your tracks but if this one customer causes such a ruckus and decides to call the police. Guess what, the police will come to scene ask to see the authorization to work on their vehicle and deem it a civil matter. They will tell the customer to go to Civil Court and file a small claim suit against us. They will tell us (Windshield Repair Person) the same thing....go to civil court and file a suit for your money. It doesnt matter it is a NO WIN situation w/o that signed authoriztion piece of paper.
This is just my opinion. I know some of you will say I am crazy and mock this response but if this one customer ever started this much trouble for you, you will remember this post and say hmmmmm maybe their was some truth to this post.
All said & done just make up an authorization for the customer to sign...its only a signature, it takes all of 2 seconds to sign. It doesnt show any distrust in your work, it just shows you are professional and you will complete a professional repair.