How can consumers be enabled to 'know the difference' about the wines quality?And what can be done to ensure that such action is not interpreted as a strategy of distinction serving social or commercial interests? An interpretation of this nature would ruin the difference that producers and marketers try to establish and perpetuate, and through which they attempt to stabilize their relations with consumers. If that difference were merely a social construction or, even worse, an economic strategy, it would not with stand the accusation of serving particular interests.This is, in a nutshell, the question raised by the qualitative differentiation of wines proposed as a solution to recurrent crises of over- and under-production in the wine market through out the centuries. Through the accusations, denunciations and suspicions of the actors involved,this article describes the long sequence of solutions that have been applied for the past hundred years to this problem of maintaining the existence of qualitative differentiation of wines.Thanks to the endless efforts of wine market professionals, a complex differentiation frame was achieved that fostered the development of a market of hundred of thousands of winebrands.