Also, OP could add an OCEAN score or similar using broad questions to get a sense of where a user is coming from. As soon as a site gets big enough for abuse, it seems simple voting has always broken down quickly.
This is a good idea. In fact, it might be interesting to include answers to these questions as part of a user's profile. So if you're curious about the particular political stance of a fellow user, you could look at their profile and see their answers to a handful of political index questions.