I'd always assumed that the type of people who attend focus groups would be closer in appearance to bottom-feeders, people who didn't have jobs or hobbies and have three hours on a Tuesday afternoon to show up and give their opinions on facial tissue dispensers. People who expect to get paid for merely having an opinion. That said, as lucrative as entry-level administrative jobs in the healthcare industry are, I make up a considerable part of my income with odd jobs like babysitting, cat-sitting, just being around when free things are handed out, and recently, focus groups.
So based on my hypothesis, focus groups aren't supposed to make you feel dumber because while you thought it was a paid session about social networking web sites, it was actually about NASA, which you happen to know very little about. I wish I could have had some time to prepare. Although I am aware of NASA's continued presence and have seen some images of Mars and have heard about the crazy astronaut woman who drove across the country in homicidal pursuits, etc., I don't think I've really thought about NASA since high school.
That, and the fact that everyone else in my peer group was either enrolled in med school or preparing to become a diplomat. I made up for my ignorance of how NASA invented LASIK eye surgery or precisely what the International Space Station was with overt skepticism. Kind of like answering every question with another question. NASA doesn't like it when you use the word "propaganda" too often. Or when you look at them dubiously when they talk about the moon landing.