Among the advantages of being holed up in one of our nation's most liberal towers of ivory is that I get to find out about things before they get published, like a recent study forthcoming in Communication Monographs.
A few of my colleagues exposed about 120 undergrautes to about 135 minutes (6 episodes) of Queer Eye for the Straight Guy under the guise of a class, and measured their attitudes towards gays before and after using an established scale for measuring these sorts of things (ATG, Attitude Towards Gay Men Scales).
Their conclusion was that exposure to six episodes of the show changed prejudicial feelings towards gay men by about 10% on average. Interestingly enough, the researchers did not monitor the change in direction, as to do so would be to make a judgement about what it means to be gay, which they did not want to do, but the bottom line is what you watch is affecting you whether you are aware of it or not.
P.S. They did a similar study with an English transvestite comedian, and found a 14% shift in attitudes toward transvestites. No, I'm not making this up.