Snob appeal refers to the qualities or attributes of a product that might appeal to a consumer with "snobby" tastes. It may refer to the actual product itself or the exclusivity the consumer could potentially experience as a result of owning the product that is being advertised.
In Simple Words,
In this advertising appeal, people are induced to buy a certain product so that they can stand out from the crowd. It is often indicated that buying that product will make them look different from the rest. It is indicated that the product is not affordable for common people. A sense of exclusivity is attached to the products.