Yes, I suppose that's true, but most users don't keep currupt files, and even if they do, you just have to redownload it. Only takes a few seconds. Besides, when you download the file that has the least amount of users, there is sometimes (more than not) a reason why there aren't that many users.
I always download from the most users, and I don't have a problem that often. (Of course I'm only downloading songs I own legally.
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