To be honest, it's kind of creepy. I just identified myself, and they somehow knew what month and year I purchased my car, a list of names I may or may not have been 'associated' with, a list of counties I may or may not have lived in, and stuff like that. I'm not particularly comfortable with a company knowing that much about me, but it's already complete so... horse, meet barn door? I wish they would at least tell…
In many cases (I haven't tried this one in particular), the site you're visiting does not see the questions and answers, so only organizations that already know every detail of your life get to see them.
They seem creepy, but you have to ask yourself: why wouldn't some company know my address and who else lived there at the same time? The companies that send me catalogs and pre-approved credit offerings certainly know. (I forget the entire list of questions, but all the ones I've seen lately are address-based.)