I just recently got my 2002 LeSabre. The wheels looked like they had never been cleaned. There was greasy black baked on brake dust all over and in between the spokes. I thought the wheels would be corroded underneath the grime, but they weren't.
A couple of different brands of wheel cleaner that I had did very little. I ended up scrubbing them with Krud Kutter degreaser and a toothbrush. I had to keep going over them, 6 or 7 times, with a little more grime coming off each time. For the most stubborn areas, I scrubbed with a small piece of green Scotchbrite, keeping it wet with the degreaser so it wouldn't scratch the finish. For the tight spots between the spokes, I wrapped the Scotchbrite around a large screwdriver.
Finally, all of the black grime came off and the sparkley metallic silver finish was still smooth and shiny underneath. At that point, I waxed them with the same carnauba car wax that I use on the rest of the car.
I can't quite tell if yours are permanently damaged or not, but a lot of those brown / black dirty areas on yours looks like how mine looked, so it may be worth some time and elbow grease. Also, I did mine while the were still mounted on the car.
