So it's a good time to review the strengths and weaknesses of polls. In fact, a poll from the Pew Research Center showed that Americans are less engaged in the campaign than in 1996. Less than half the public is following the conventions. Polls are snapshots. They measure voter sentiment at that moment.
Trends are more useful than a single poll.
A poll from an independent group or a news media organization is more likely to be objective than one from a political party or interest group. Polling organizations like Gallup, Harris or Roper have track records that lend them credibility. Sometimes that is difficult. For instance, a Pew Research survey of independent polls after the 1998 state elections showed that Republican Party strength was consistently overestimated because the turnout among Democratic Party voters was underestimated. Some readers can't believe that a survey of less than 1,000 people can represent the nation as a whole.