Recently, I have also noticed a negative trend of selling untested hardware by Chinese sellers on ebay.
After many experience with Chinese IC sellers I think: exist a big chinese factories which are buy tons of electronic waste. Remove the ICs from old PCBs and refurbishing these.
The problem: not sell these as used, refurbished and untested components with their original label.
Make a fake new chips: remove the old labels, print a new one (with a best of the current type parameters), polish the pins, and sell as brand new.
Some examples:
-I bought 10 pcs 20MHz CMOS Z80 CPU. Tested on 10MHz, only one worked. Another ones are old slow NMOS CPUs. After reclamation the seller send another 10 CPU. Summary of the 20: 3 total dead, 16 are NMOS, and works at max 8MHz, only one are CMOS and works on 10MHz.
-4xWD1772PH 02-02. Real type are WD1772PH 00-02 (can't overclocked to 16MHz for HD disks)
-5xAMD 29F040. Realy type Macronix 29F040
-4x27C256-70. Real manufacturer are different than the labeled. Access time too slow, probably only -150. One are dead.
-2x27C160, one are dead
If you want a relaible components then buy from TME, Mouser or other similar reliable companies. But these not too cheap...
Buying from China are lottery game...