I invented POCO ratings a few years ago. POCO = Portable Contacts. It's just a glorified address book, that ignores the platform (eg, you only have to connect to somebody once, and you're connected to them. Full stop. That is, you don't have to add them on Facebook, and then on Twitter, and then on Google Plus, and then....you just add a reference (automagically) to their existing entry.
Then, when you're looking at reviews, instead of looking at what random strangers have to say, it just looks up your friends, and friends of friends, an optional number of levels deep.
This idea failed, but not because it wasn't good. It failed because POCO just didn't really take off, and through personality politics (I wasn't tactful in pointing out the failings of the other developer involved in this particular project, and that was a fight we both lost).
This is still how you fix the problem.