This is why China is going through all of the effort to keep the debt hidden. One really big problem with state-backed business is that the credit-worthiness of the business is fundamentally tied to it's backer.
If your doing business in China, massive debt heightens the risk that you simply won't be paid. The real risk here is ever tightening controls on Chinese borrowing and investment dollars flowing in. That would have a crippling effect on overall growth.
What about interest payments? What about the risk of having the debt called in, or the risk of using up all of one's credit?