I'm probably going to get slaughtered for saying this, but after spending a couple of days thinking about it, I think that the tracks are probably as genuine as they can be and I don't think anyone is trying to fool us.
I think they found some great song concepts, some great "single-takes" and some radio-friendly ideas and did the best they could on them. I also think the recordings they did have were probably rubbish quality and needed serious work to be audible, let alone releasable, and I think it's this that has caused the confusion. Perhaps they have "over-corrected"?
Either way, I find it hard to believe that an organisation would pay such huge amounts of money for tracks that aren't real. I also find it hard to believe that a great number of professional people would come forward and say that the tracks are Michael's if they weren't. Keep in mind these people have careers that don't necessarily rest on Michael's legacy, but saying the vocals are MJ's only to be proven wrong later would be beyond devastating to their professional lives. I honestly believe that these people are saying they're Michael's vocals because they are. They're just really rough vocals (not because of Michael, just the recordings themselves).
I think some group of people out there, or maybe just one person, is trying to disrupt this process for some reason. Perhaps the conspiracy is the talk about the tracks being fake, not that the tracks actually are fake?
Ultimately, you need a lot of people to keep a valuable secret for something like this to happen. I don't think that you can achieve that when money talks the way it does. I think the tracks are probably real, they're just not what we expected or wanted.