Just wanted to share my experience with you. It just convinces me, that there are no way of telling for sure if the brushes are real or fake.
Bought a couple of brushes some time ago from a site similar to Ebay here in Denmark. The seller bought them in the states and sold them in Denmark, where the brushes are twice the price of what they are in the states, so it seemed reasonable enough.
I actually used the brushes for some months. I bought two 239's and I already had a 239 bought at the local Mac Store, so I know for sure, it's genuine, and I could aboslutely not tell any difference. They looked EXACTLY the same.
But I also bought a Blush brush, and that came i a hard plastik sleeve. Some months later I realized that ment, they were fake, I contacted the seller, and she gave me a full refund, and seemed truly suprised and sorry.
The thing I wanted to say is, that the blusher brush was clearly fake. But the two 239's? Well considering the other brush was fake, I am quite sure that they were fake too. But when I realized the blush brush was fake, I read this and 117 others guides to validating your brushes, and could still not see any difference between the tqo fakes and the one I bought at a MAC store.
The handles and bristles looked EXACTLY the same. The print felt the same and could be scratched a bit etc. etc. And I looked VERY VERY carefully! They could be real, they could be fake, I will never know for sure.
So... I guess I just want to say, you can never be sure...