They know exactly what they're doing. It's an amazing step forward for the music industry. They seemed to be stuck in time and then all of a sudden they're agreeing to give pirates good quality files in return for a fee. This isn't a sting. Beyond being technically impossible to tell if your mp3s weren't purchased it would also be a violation of the ITunes user agreement and probably a bunch of local laws.
Although, I admit, the paranoia people are exhibiting is somewhat entertaining.