I understand. But how do we know the real cost when the country we are talking about is China? Even in transparent economies like the EU, you find convoluted ways to subsidize companies (or convoluted ways to accuse companies of receiving subsidies - depending where you stand in these issues)

Because they aren't being convoluted about it, their costs and subsidies are very obvious. They are simply losing money and keeping the mills going via state guaranteed debt (well, the banks are being ordered to lend).