So... it's pretty easy to find reviews that you are confident are fake, and you're probably right about most of them.

But that only leaves us an uncorrupted signal if, given a review you have deemed authentic, it actually has a good chance of being so. Do you know that that's the case? How?

I'm not sure it's true in your case, but statements like this are often made when people don't realize they're (implicitly) marking their predictions against those same predictions.