Many opinion pollers do badly when it comes to predicting elections. This is mainly because they let their respondents self-select them into their polls. So what, who cares? The polls make for some good entertainment and easily fill the talk-shows on television. If everyone knows they cannot be trusted, why care?
We should care. In the Dutch electoral system - with poportional respresentation - every vote counts. If only a small percentage of voters lets their vote depend on the polls of the election result, this can result in shifts of several seats in parliament.