When I sell a car, I am as honest with people as I can be. I answer any question given, honestly. If there is rust, I am going to remove it, and tell them how I repaired the area, or I will leave it, and tell them that also. I will not place a product(POR or anyother) over it and say I fixed it. I may not know every inch of a vehicle that I am selling, and in those cases, I make that known also. I do not have the time to worry that someone may be upset with me because I lied to them, and have to watch my back. To remove the rust, and replace the metal, is the best I can do. I, along with everyone else, cannot guarantee that it will never rust again. It just will not be the rust that was there before, coming back.
Ten years ago, I did a car for a friend. It had alot of rust damage to it. All of the rust was cut out and replaced. He had the car painted by someone else, at considerable expense. I saw the car about a year ago, and it looked great. I wasn't really crazy about the paintjob that was put over all of my hard work, but it wasn't my choice. I knew that my work was going to be under a very expensive paint job, and it better be right. This wasn't just a repair job, it was for a friend. He knows where I live and how to find me. He knew everystep that was taken on his car. I did everything that I could to prevent rust from being a problem later. That friend moves around alot, but I have no concern about running into him because of the repair on that car.