That may have been the case buying some tat from a lucky lucky man on holiday but the decent oakley fakes you get these days are top quality.Fake sunglasses can be quite bad for your eyes.
If they dont have the proper filters to block the harmful light but are dark so they dilate your pupils and actually let more harmful light in than if you werent wearing anything.
I use a real pair of photocromatic rudy projects but on mega bright days I will use my fake oakley, I have a pair of recent radars and jawbones both have interchangable iridium and polarized lens, I mean you can see that they have been correctly coated and you can test the polarization yourself.