There is some truth to that, for sure. The problem comes when you cannot determine if the part in question was actually made by the company on the box, or that said company merely provided the label on the box.
Many, probably most, of the major auto part manufacturers DO indeed have a plant in China. And, they probably do exercise the best QC they can at those plants, same as they would anywhere else. But if the want an aftermarket "full coverage" option for all kinds of things, then they often do the rebox route. And then, that QC can become suspect. I see that with a LOT of things, with a lot of well known brands.
I was made aware of it first many years ago with Bosch, when I worked at a local wholesaler. We purchased items directly from Bosch, we were this region's distributor. Bosch wanted to offer full coverage of ignition, fuel, filters, rotating electric, etc. on everything. Problem is, Bosch didn't make everything. So, a Bosch distributor cap, for instance, was OEM on a Volkswagen. And it was EXACTLY the same as the car left the factory with. But on a Toyota, it was crap. Denso made theirs, and Bosch couldn't/wouldn't rebox one of those, so they found some garbage from (at the time) Mexico. It was HORRIBLE quality. The fit was bad, the performance was marginal, if they even worked at all. Yet both came in the familiar yellow Bosch box. Same for filters. Bosch contracted out to Purolator or Champion Labs for much of the stuff they didn't make, which outside of a few gasoline and diesel filters for European brands, was nothing.
