This sort of crap does not only happen through eBay.
A manufacturer on the Chinese side was assembling an engineering build of 100 8-layer SMT PCBAs with BGA's, UDFNs, QFNs, 0402s etc for me. No problems with the raw PCB, the component placement or soldering. The build quality was excellent. But they had a problem with the LCD backlight driver chip TPS61160A - a few volts output, rather than around 18V... on every board. These are only 40 cent chips from TI but the manufacturer had apparently procured fakes.
There were two critical value resistors on those boards that had to be 0.5% tolerance and I specified Yageo (I have
never had a problem with Yageo). It turned out they some were as much as 1.3% out - some high, some low in the same batch. This caused problems, taking a lot of my time debugging the issue. The manufacturer blamed Yageo. Then they said maybe their reflow oven temperature profile was set too high. To feed me such

leads me to suspect they most likely they cheated by using generic resistors than Yageo's quality resistors or they bought fakes - probably the former.