Seller deceive a buyer by using A. BAIT AND SWITCH.
Seller lures the buyer into buying a product, bait. Seller presents all benefits of the products using the bait product. When the buyer decides to buy the product, the seller will then switch the bait product into another product that may be of lower value than the bait product.
In the event that the buyer will complain to the seller regarding the product bought, seller will defend him or herself by insisting that the product given was the product tested by the buyer.