This week's edition of the Economist has an excellent summary of the problems with goods imported from China -- not only the recent brouhaha over seafood, but also the earlier issues with tainted toothpaste and, of course, pet food.
The key points:
Poor countries where manufacturing is booming often struggle to maintain quality standards at first. ... But the Chinese government's reflexive secrecy, as well as widespread corruption and tight curbs on the press, probably make matters worse.
After all, in America as in most countries, only a relatively small proportion of imports is inspected. Moreover, numerous agencies have the power to monitor and block shipments, creating a bureaucratic quagmire.
Also, the Chinese government has been harsh in punishing those responsible (in its view) for dangerous and/or contimated food and drugs. The head of the country's food and drug administration was sentenced to death in May, and last week the government sentenced to death a former department head from the same organization.