If you are an American citizen the certificate of marriage-ability as it is called is required by the Chinese government and the US Embassy will run your name through the FBI, US Marshal's Service, US Consul Look Out, IRS, DHS, and other agencies while you wait. If there are any flags on you the passport will be seized by the US Consul. If you see any American that was married to a Chinese person, it is a safe bet that they are in the clear because if they were not, it is highly unlikely they could be married in China because they need a passport to register the marriage at the Chinese marriage offices. Americans will be run for back taxes, child support, wants, warrants and criminal history while they wait at the US Embassy and that is also why they now require your name, dob, and passport number to make an appointment for any American Citizen Services. There is a little more to the process than you might be aware of. This process is also done for any services such as extra pages in your passport, notary, etc. Enjoy your visit to your embassy.