Much of what we think of as perceptions of the world are really educated guesses based on past experience, and when we're primed with an idea about something before actually experiencing it. we tend to agree with whatever that initial expectation was and ignore what we're actually thinking. When we're told that something will be good, we tend to believe it's good, especially if we're told by an expert. Whether it's movie reviews, book reviews, or music, our expectations often outweigh the more critical side of our brains.
This is especially the case with foods. A recent Lifehacker article pointed out there have been plenty of studies showing how our expectations change our perception of taste. For example, one study tested the role of expectation on taste using a highly novel food, smoked salmon flavored ice cream. The study found that when people read the label "ice cream", they disliked it and found it salty and savory. But when the food was labeled "frozen savory mousse," people liked it more because they weren't expecting the usual sweetness of ice cream.
In a study published in 1964, researchers looked at how beer brand labels affected taste. Researchers asked brand-loyal college students to rate a bunch of unlabeled beers. In general, participants of the study didn't seem to discern the taste differences among beer brands when they weren't labeled, which suggests the brand name has a pretty big impact on how much we enjoy something.
Wine is a classic example of how expectations alter our perception of quality. Coke rates higher when consumed from a cup with the brand logo, the presence of the word "soy" on nutrition bars makes them taste more grainy, and coffee tastes less bitter when we're told it's not bitter. Researchers found that when people were told a comic was funny, they tended to agree, even when it wasn't.