some Chinese bearings do seem a bit iffy .....
i got a replacement set for a taper bearing hub a while back from the nearby farm shop , and found out that their Chinese ..they were certainly cheap ...(but easily available
)
(on suggestion)... i washed them out with carb cleaner spray into a cup , and oddly there were some very fine iron fillings in there (putting a neo on the cup side would show them up)...more like fine dust particles than any thing else , but unwelcome guests all the same
i repacked them and used them anyway ...time will tell
the ginlongs seem to have sealed bearings ......(no easy way to take a peek)
its very odd with Chinese manufacturing ......they seem to go from one extream to the other