From Why People Buy by John O'Shaughnessy:
"[I]ntrinsic preferences can be a problem to identify. In the first place, consumers find it difficult to verbalize what it is they like about a product. One reason for this is that we do not have a rich vocabulary for expressing different types of pleasure and liking. In the second place, consumers may only seem to choose on the basis of intrinsic preference. For instance, the theatregoer may or may not choose the play most likely to be enjoyed but may consider which play is best for impressing friends. Preferences in beverages and alcoholic drinks are notoriously influenced by product image. Thus, although U.S. beers are becoming more bland and homogenous in taste (so that in blind taste tests consumers cannot distinguish between them) beer drinkers still demand some particular brand--the brand with the image with which the drinker can best identify."