It probably ticks them off that people circulate links to their polls in forums like this. Those who aren't content will vote.
No, I don't think it does. They are well aware of how people respond. And, by tracking votes over time, they can plot the posting of the poll's link to forums.
One poll that keeps being past around is in fact only kept available just for the purpose of tracking the socialization amongst ardent supporter and detractors. The poll results themselves are irrelevant and aren't even available by "drilling down" from the sponsors main web site.
I can't find how to "navigate" to this poll or it's results from MSNBC.com so only those of us who are passionate about the question and are Internet/forum active will probably ever see the results.
One thing polls like this can indicate is who really has the better, or at least most responsive, grass roots. Both by the outcome, the quickness of energizing the responses and the longevity of the responses.