Some Stanford researchers have reported that the US consumption of French wine seems to have fallen by over 25% in 2003 thanks to l'Escroc and Vile Pin's efforts to derail the Iraq invasion. As the paper's abstract explains (PDF)
The French Opposition to the war in Iraq in early 2003, prompted calls for a boycott of French wine in the US. We measure the magnitude of consumers’ participation in the boycott, and look at basic evidence of who participates. Conservative estimates indicate that the boycott resulted in 26% lower weekly sales at its peak, and 13% lower sales over the six month period that we estimate the boycott lasted for. These findings suggest that business should be concerned that their actions may provoke a boycott which hurts their profits. We also find that neither political preferences or media attention are important determinants of boycott participation.
I wonder if one reason why this boycott worked is that there are plenty of alternatives at similar prices.