It shouldn't be surprising, but that Cabernet Sauvignon that Robert Parker rated at 95 points will, most likely, actually taste better to you once you are aware of the rating. The research doesn't come from the world of wines, but rather from brain science. Harvard researcher Jamil Zaki showed men photos of women, and asked them to rate them for attractiveness. Then, he showed them ratings from a "previous group" that were, in fact, random.
As expected, the men's ratings changed to match the consensus scores more closely. However, Zaki's team found that if the participant decided a woman was more attractive than they first thought, there was a spike of activity in the orbitofrontal cortex and nucleus accumbens; if they decided she was not as pretty, activity decreased in these areas.
Previous research has shown that the higher the activity in these brain regions, the more a person values a certain stimulus. In other words, the researchers argue, the participants were not just modifying their appraisals for the sake of appearances: the so-called average results had genuinely changed their opinion of the photos. [From New Scientist - Following the herd actually shifts your opinion by Ferris Jabr.]
The key finding isn't that people tend to shift their expressed opinions if theirs is out of line with everyone else, that's well-established. Rather, the brain scans showed that when they adjusted their belief to conform with the norm, they REALLY believed it.
Although this study used photos, the idea that our true perception of a wine is influenced by what we believe about it has been studied directly. We know that expensive wine tastes better (even when it's cheap plonk).
In Why You Should Serve Cheap Wine I outlined a strategy for pleasing your guests with inexpensive wine. To update that strategy, find a cheap wine with some good reviews and, partway through your tasting, share those reviews with your guests. (Of course, in that strategy you are already fibbing about the price, so I suppose you could make up the high ratings, too.)