When I ran a body shop, there was absolute zero warranty on a "customer prep" paint job. Yes, I'd shoot the paint, and do as good a job as possible, but having no input concerning the methods and materials used in the very essential steps of sealing, priming, sanding, etc. made it impossible for me to guarantee the outcome. My pet peeve was someone who spent months getting a daily driver ready to paint, and left primed areas exposed to rain, road grime, etc. Primer is porous, and it sucks up moisture and contamination like a sponge! Lay a top coat over that stuff, and it's a disaster waiting to happen!
Jerry
