Somewhere in related posts I learned about the Android app called ELM327 Identifier. This may be helpful in evaluating the quality of a chinese clone ELM327 device. It tests a device's responses to the eleven different versions of the ELM protocol released to date.
Results
I lucked out. My cheap eBay knock-off purchased 5+ years ago passed all but the v2.3 tests - which makes sense since that was released only 3-4 years ago.
My device has an an arbitrary MAC address, which can be an easy way to spot an imposter (as opposed to 11:22:33:aa:bb:cc or similar). But it does report as an ELM v1.5 device, which was never actually released by ELM.