Unfortunately, it is true, the Xbox 360 reports of getting scratched disks are continuously rising. A solution for it is yet to be found but it has been determined what is causing the damage. The people over at Llamma.com decided they were going to figure out the cause of their frustration:
We started by disassembling of our one of our Hitachi-LG GDR-3120L DVD drives, which happens to be the only drive in any of our 360’s. Upon inspecting the laser assembly it was obvious there was only one small area that could have caused this. I applied some silver sharpie marker over the entire black laser assembly housing and reassembled the drive. I threw in the Quake 4 bonus disk and waited for the small jet to take off. After the disc spun up I went through the tilting motion a few times. Video(1.5MB): How to scratch a disc with an Xbox 360(mirrored courtesy of Xbox-Scene.com thanks!). We then disassembled the drive to find what was causing the scratches. The following photo shows exactly where the problem occurs. As you can see the black showing through the silver area that was painted.
News Source: Llamma