I'm well aware of the notion that they are capable of higher quality, but in talking with a number of importers, it seems that most of them complain that the initial quality is very good, and then it systematically declines slowly to the point where it becomes necessary to do an incoming inspection on every single part if they're critical parts. My understanding is that the Chinese government encourages it's manufacturers to cheapen the product over time as a cost saving measure. There's a story going around of some sort of structural item that's used in building construction that was found to have lost 10% of its mass over the production run.
One importer of speaker drivers that I've talked to said that at one point it got so bad that he had to reject 50% of the drivers he received. His initial rejection percentages were somewhere under 10%. This huge rejection rate pushed his costs up high enough that I believe he eventually found a new manufacturer on a different continent. I certainly don't have first-hand experience with these products, but I have had conversations with the guys who design and contract companies to build their products, and I've heard the same story from most of them, so I tend to believe that it's got some legitimacy. Your mileage may vary.
I know that many larger companies have had to resort to putting quality control reps at the factory to help mitigate these issues.