According to Karl Marx in Capital, when we participate in commodity fetishism, we focus so much on the end product that we tend to forget there was ever a human being involved in its production. Once the end product has been assigned a value and is put up for sale, the object itself becomes overly important and anticipated—to the point of fetishism.
In Capitalism, Marx is critical of commodity fetishism because he feels it is another way in which people in society become separated from one another. If the purchaser of a new product is solely focused on the new purchase (rather than on the production of the product), there is no opportunity whatsoever for social interaction of any kind. As Marx himself notes in Capital:
Capital becomes conscious of itself as a social power in which every capitalist participates proportionally in his share of the total social capital.