Most chinese gh is shit because manufacturing growth hormone is MUCH more complicated than making regular hormone powders, like test, deca, etc... It's also the reason almost all the UG halotestin is shit.....Much harder chemical to produce.
Plus it's more complicated and expensive to analyze GH so the customer can't verify his batch easily. But the Chinese have the capability to produce very high quality GH, no doubt.
Another reason for the low quality GH is what happened with Jintropin, and how the Chinese government was "forced", by the US, to clamp down on GH produced openly for the international black market by known actors.
The Chinese can't produce and export it openly anymore. So now you only have back door products of unknown quality.
If China stopped producing hormones overnight it would kill pro bodybuilding until someone else took over. Probably at least 95% of hormones used by bodybuilders today have China origin.