something that came to my mind. let's say there's a new song of "Pitbull" on iTunes but u dont actually have the song. What stops u from tagging a completely different Pitbull song as the one and u get it for free? ^^
That won't work. I can almost guarantee apple won't simply be checking your tags to verify the song. I'm guessing there will be some spectral analysis of some sort to make sure it matches up.