When we first started importing activated carbon from China 20 years ago, we invented a system that worked quite well. Of course, having the president being able to speak Chinese helped at the time helped, but now it is no longer a necessity.
What we did was to establish a secure warehouse at the port in China. Our manufacturers were given clear quality specification and the methods that those specifications will be inspected to. The manufacturers will deliver their products to our secure warehouse, where it was kept under lock and key. Then we will sample the products and express the samples to a trusted lab in the U.S. Only when the results are satisfactory were the products loaded into containers, under guard, locked, and loaded on board. Any rejected products were the responsibility of the factory to take back. Later, we qualified a laboratory in China and they faxed the results to us. Once in a while, we will deliberately give that lab a defective sample of known poor quality to keep them honest.
This way, you do not get rejects delivered to you in the U.S., resulting in subsequent payment arguments and losing a half way decent supplier and having to re-quality a new supplier, which may not be any better.
Unexpected goofs nevertheless still happen, but most of the more common ones were stopped at the other side of the ocean. An example of one we did not catch, and is an example of cultural barrier, was when the factory hired a new worker. When he saw the carbon scattered on the ground during the bagging process, his frugal instinct took over, swept them up with his straw broom, and put them back into the bags. The quality sampling did not catch that but the straw clogged up the water filter in the U.S.!