In addition to my 4 layers of protection, I usually run these "sandboxed," so they can't interact with my computer if they wanted. That said, you're correct about most, though, particularly someone who marks it "like" on Facebook. They got you then...Oh, I'm sure there is one. Certain inputs guarantee a specific output.
That said, I'm pretty sure that all these 'internet quizzes' are merely for building databases to sell to advertisers.