Intensity and focus subvert general democratic sentiment.

 From Links to Consider by Arnold Kling.

The polls do not tell you the intensity of feeling. A minority of voters who really care about an issue can overwhelm a majority who are mildly on the other side.

A perpetual issue in resolving public discourse.  Tightly tied to the issue of fanaticism.  In fact, I think there are three linked issues which traditional polling cannot pick up.

Which way do you feel about the particular issue (traditional polling)?

How strongly are you committed to your response?

How singular is your focus (how many other issues are there which you consider important)?

If there are one hundred people who are roughly ambivalent (say 48:52) about the proposal, are only lightly committed to it and have a broad range of other things they consider important, you will end up with a dramatically different dynamic and outcome than if ninety-five people are as described but five people are very strongly committed to their position and are monomaniacal in their focus.  

In the latter case, the fanaticism and monomaniacal focus can lead the group decision-making to entirely different outcomes than would be acceptable to the ninety-five.

I was once on a neighborhood board and there was a very pleasant member absolutely committed to, and and only interested in, converting 15% of road surface into designated bike paths.  He was persistent year over year and even though 99% of all traffic in the neighborhood is by car, 15% of the road surface was converted into designated bike paths.  Which remain virtually unused because they are not particularly safe and virtually no one bicycles anywhere (more people walk to work or walk to stores than bicycle.)