You know, quite often these days the fakes are produced in the same factory as the originals. That is how they get them to be so authentic. They run the same designs out of hours making a few shortcuts. Either that or someone leaks all the design data to a competing factory.
I had a fake Jabra bluetooth headset off ebay. Confirmed fake by Jabra. The audio quality was almost indistinguishable from the authentic ones and included all the same features and presumably that means the same electronics. Also the box was indistinguishable apart from a tiny bit of a misalignment in the different inks used around the hologram (which was also done perfectly).
You can't trust anything except Authorised dealers really.
Yeah it's very hard to figure out which ones are fake these days. The quality, design, performance are very identical to the real ones. The only thing they don't have is warranty.