Read of a fascinating survey recently.
People were given a glass of Californian wine or a glass of North Dakota wine, along with a piece of cheese, and
1. Asked to rate what they expected the wine to taste like before they tasted it;
2. Asked to rate what it did taste like once they had had some; and
3. Asked to rate the cheese that they were given with the wines.
Unbeknownst to them the wines (a cheap cabernet) and cheeses (mild goat cheese) were identical.
The results were as follows, rated out of 9:
So the participants expected Californian wines to be twice as good as a North Dakota one. Once they tasted it they didn't change their rating if they thought it was from California but improved the rating for the North Dakota drop.
Interestingly, when the cheese was being drunk with what they thought was a good wine, it rated much more highly.
Appearance is everything, it seems.