I don't know, I think a test like that would rather proof lazyness than dumbness. I would also assume people that actually know that stuff and are educated would much more likely coincidentally mess off a question than someone who has no interest in politics and googled that stuff 1 hour early. I don't think it proofs anything.
However, I do understand your point and would like it if only people you have taken time to form an opinion would vote, but I don't know if there is a way to assure it even a little.