Cut the guy some slack, guys. Not all disc related problems is due to pirated stuff. I can help anwer this for you: yes, DOA4 has issues. I don't know whether it's more of a quality control issue or tech related issue. You see, the DOA engine, which has been used since DOA2 uses streaming data instead of traditionally loading levels in between matches. The result is a game with minimal loading, so you don't see too many loading screens.

Is your game not loading at all, or does it get stuck somewhere? For me, I can only get up to the Team Ninja logo, and then the background goes dark. Wait a while longer, and the 360 returns to the dashboard with an unreadable disc error. Retrying again brings no improvement at all. This is the only game I have with this problem. Not every DOA4 owner has it, though. Not sure whether this is an insolated case.

Lastly, no amount of polishing seem to help. For me at least, it doesn't seem to be the disc's fault, so it must be tech related (see above). My solution was simply cleaning the 360 drive itself with a disc cleaner. Since DOA4 needs to load the game very quickly, there can't be any problems during disc read. Cleaning the drive may help improve the situation for you as well.

Have you tried clearing the Xbox 360's hard drive cache? Streaming games (like DOA4 or GTAIV) do a lot of data caching. Clearing the hard disk cache may help. It's actually a feature built into the 360, though not many people use it. Check it out here:

http://support.microsoft.com/kb/907586

Although the article covers screen freezing, clearing the cache can also help with read related problems. Just have a go and see whether it helps.