Scott Rasmussen of Rasmussen Polls answers a question about what is meant by "likely voter".
When you read the polls at Pollster.com, you will notice the designation "LV" next to the results reported from Rasmussen Polls. "LV" stands for "likely voters." In his answer to the question, Scott Rasmussen admits that minorities and young people generally do not qualify as likely voters, or at least are less likely to qualify. As such, their opinions are simply not counted to the poll results.
WHAT THIS MEANS, oh you FoxNews loonies, is that when Fox News reports that the President's approval rating is below 50%, what they are really saying is that the President's approval rating is below 50% if you disregard the opinions of two giant segments of his supporters.
THE LESSON. I rarely get into a discussion about politics with a Wingnut when they don't cite to some Rasmussen Poll or another. Since these poll numbers are unreliable, they actually undermine the propositions for which they are cited. Do not use Rasmussen Polls as support for arguments.