Reading the links, the one mentioned error by the whistleblower was actually just an example of real data contradicting the official lies. All the other mentioned criticisms are one of surface style.
What I personally found most interesting about this was not that the whistleblowers were discounted before and after they were proven right (we see this in many bubbles, for example, the housing bubble, and apparently it's not yet certain that Sino Forestry is a massive fraud), but how one could use a sort of Outside View/Fermi calculation to sanity-check the claims. If Sino Forestry was really causing 17m cubic meters of wood to be processed a year, where was all the processing? This basic simple question tells us a lot.
I'm personally wary of hindsight bias sort of stuff. Of course this all seems obvious to us now, but... would it have when we first examined it? I don't know.
I recommend John Hempton's blog post on how badly people judge seeming madmen in the case the conventional view has only conventional-wisdom support. I also like how he explains his research and conclusions in general.
the gist: