Remember, too, that polls have a very short half-life. Reading a poll that was "in the field" a week or more ago, is as useful as trying to pick a stock by checking the Dow Jones Industrial Average on October 3, 1951.
Finally, look for who is included in the sample. "Adults" is a useless measure. "Registered Voters" is somewhat better. "Likely Voters" is the gold standard at this stage in the campaign.
Many in the Professional Pundit Class hold that debates don't change voters' minds. That might be true, but with the polls this close it doesn't take many potential voters seeing something they like - or dislike - in one of these guys to start a real move toward or away from them.