Some types of premium goods (such as expensive French wines, or celebrity-endorsed perfumes) are sometimes called Giffen goods—via the claim that lowering the price of these high status goods decreases demand because they are no longer perceived as exclusive or high status products. However, to the extent that the perceived nature of such high status goods actually changes significantly with a substantial price drop, this behavior disqualifies them from being considered Giffen goods, because the Giffen goods analysis assumes that only the consumer's income or the relative price level changes, not the nature of the good itself. If a price change modifies consumers' perception of the good, they should be analysed as Veblen goods. Some economists question the empirical validity of the distinction between Giffen and Veblen goods, arguing that whenever there is a substantial change in the price of a good its perceived nature also changes, since price is a large part of what constitutes a product. However the theoretical distinction between the two types of analysis remains clear, which one should apply to any actual case is an empirical matter. Based on microeconomic consumer theory, it assumes that the consumer could value a good without knowing the price. However, when the consumers who were constrained by income and price need to choose the optimal goods, the goods must be valued with available prices. Because, in some degrees, the higher price indicates higher values of goods offering to the consumers.
