Not only does the general public do a lousy job of answering political knowledge questions, it also suffers from statistical innumeracy. In other words, we suck at estimating risk, at how much the government spends on foreign aid, and -- it seems -- how many gay people there are out there.
A new Public Opinion Quarterly study by three people (two of who I took for class as a grad student!) looks at homophobic innumeracy and finds that, indeed, the public is bad at this. Then again, the public is bad at estimating the size of other minority populations. As the authors note, people "aim high" in these estimates.
People in the certain demographic groups aim the highest, or "mis-estimate" the most: woman, less educated, blacks. Not coincidentally these folks also tend to score lowest on political knowledge tests. Interestingly, they find no real relationship between religious beliefs, even a literal interpretation of the Bible, and overestimation.
Following politics was associated with less overestimation. Or, I suppose, more accurate estimation. Unfortunately that's as close as the authors get to a media variable. I'd love to know whether exposure to the news made one more or less likely to overestimate the number of gays and lesbians in society. My guess is that media exposure would lead to greater overestimation by segments of society. Why? Because you see gays marching or protesting or dealing with some legislation on the news, you're more likely to think there are a lot of them, or at least more of them than exist in the population.
The funny part is, there are people who argue about the numbers here. It's one of those great debates, like what's the actual number of people who attend religious services. It all depends on your methodology.