Things They Should Invent: demographic poll of the kinds of people who answer polls

Have you ever seen a poll published in the newspaper and though "WhoTF answers these poll?"

Have you ever declined to answer when a poll called you up? Have you ever just not answered the phone when an unrecognized number came up on your call display?

They should have a research company call people up, say they're doing a poll, and then just poll demographic information. Then they should compare that information with the available census data to see if it is truly representative.