i talked to a reputable body shop out here to paint my new side skirts,well used side skirts anyway, and they said they have to use a special primer, but its not a typical primer, its like a base coat they have to do to it, before the paint, or the paint wont stick. So i dont think your guy was bs-ing you, there is a certain base coat they have to do before they spray the paint. What that base coat is called, i forget, but its like a primer for urathane..