The guardian has a nice article on "Wine-tasting: it's junk science" by David Derbyshire.
"Results from the first four years of the experiment, published in the Journal of Wine Economics, showed a typical judge's scores varied by plus or minus four points over the three blind tastings. A wine deemed to be a good 90 would be rated as an acceptable 86 by the same judge minutes later and then an excellent 94.
Some of the judges were far worse, others better – with around one in 10 varying their scores by just plus or minus two. A few points may not sound much but it is enough to swing a contest – and gold medals are worth a significant amount in extra sales for wineries."
"n 2011 Professor Richard Wiseman, a psychologist (and former professional magician) at Hertfordshire University invited 578 people to comment on a range of red and white wines, varying from £3.49 for a claret to £30 for champagne, and tasted blind.
People could tell the difference between wines under £5 and those above £10 only 53% of the time for whites and only 47% of the time for reds. Overall they would have been just as a successful flipping a coin to guess."
and here's a good one:
"Colour affects our perceptions too. In 2001 Frédérick Brochet of the University of Bordeaux asked 54 wine experts to test two glasses of wine – one red, one white. Using the typical language of tasters, the panel described the red as "jammy' and commented on its crushed red fruit.
The critics failed to spot that both wines were from the same bottle. The only difference was that one had been coloured red with a flavourless dye."
HT: Guillaume Frechette