When buying any designer brand look to see if the seller has many and in many sizes - this has been a good indicator to me that this is a business selling fakes.  Dior trainers come in WHITE boxes and not yellow as can be seen in many pictures and the dior stamp is very deep in the tongue of the trainer, the dust bags are material and not woven paper.  Don't rely on the protection of paypal or ebay or the good nature of the seller to protect you.