There is no chrome paint that really looks like chrome. How did you clean the bumper? If you didn't already know, 0000 steel wool does a great job at cleaning chrome and doesn't scratch the surface. Maybe try some on the bad areas and see if it helps. If you have spots where the chrome has actually chipped off the surface of the bumper, I don't think you are going to be able to hide it. Maybe you could find a nicer used bumper?