Did you ever check to see if they filtered UV correctly?
For the same reason, I did not risk buying plastic frames. They break/bend too easily.
I'm still amazed that Chinese factories managed to make optical grade glass, cut, and polished for glasses almost as cheap as molded polycarbonate.
When buying fake sunglasses or unknown orgin, always buy polycarbonate plastic lenses as these filter out most UV light.
It's the fake glass lenses that are a culprit and can be very harmful to your eyes.
I have tested this with a UV light.