My GH2 got scratched about 2 months back. The 360 fell over while the disc was in it and got a nice deep circle around around it. The game would load but would get a dirty disc error when trying to load a song.
Tried the windex method - Failed
toothpaste method - failed
Today I decided to give my car polish a shot. At this point the disc was useless so why not. slapped a little polish on and went to wor. I could immediately see all the little scratches get polished out. I worked alittle bit harder on the deeper circle and gave it a shot. And what would you know, the disc spun right up and is working perfectly again.
I never heard anything else on the net about using car polish even though it seems pretty easy to figure out.
Thought I'd share my success story so other people can get started at refurbing their damaged 360 discs.
Polish used : Meguirs step 7 Show car glaze