Well technically the OP is correct IMO, since DX does have those sennheiser cans its worth letting people know about it. but not everyproduct there is a replica/fake
Never seen Dealextreme sell any Fakes... Replicas and Chinese Knockoff, yes, but the review of each product is there on their site itself which can tell you about the item(s).
@OP, You cannot directly call these website as FAKE. As said by other users here they may be replica as I've shopped using 20north as well as Focal Price. I found both of them very good only thing was 20north couldn't deliver at my place.
DX cant be in that list. It has a big range, prices are according to the quality and it has original and Chinese products too. + There are user reviews and ratings on most of the products to let buyers judge. I have got great stuff from them, solely based upon user reviews.