I don't think there is as much GPU-based farming in China as people claim. ASIC, of course, maybe botnets originate in China too but I would be quite surprised if there was anything like as many legit GPU's mining in farms as people imagine. I think it's just too easy to claim China is the answer to peoples questions because in the most part its believable.
Why would that surprise you? In fact I know of several very large GPU mining farms in China (a couple of which whose operators have posted in altcoin threads on Bitcointalk) and for good reason...they are able to obtain GPUs directly from the manufacturers, before they ever get exported, on the cheap. Now, they can be the first to get the ASIC hardware AND they have the power infrastructure set up to run a gigantic number of the more efficient machines.