They are only polling the "Dubya" fanclub from 2004! All Paul supporters I know personally didn't vote for Bush (nor, in most cases, for Kerry). And, like most young people today, they don't have land-line phones, just cellular and VoIP!
And, on top of that, many instances of dishonest questioning have been documented, like excluding Paul in some key states! Some states where he's raising most money per capita and might poll in first place (AK, WY, ID) are being ignored completely! The mainstream media is giving him disproportionally little coverage... All this creates a self-fulfilling prophecy that he can't win, and it's an amazing show of strength that in spite of all that he's doing as well as he is, already breaking into double-digits in some states!
What we have here is the perfect storm of "scientific" polling being completely inaccurate, and Rudy McRomneysonabee will be taken by surprise in the primaries, especially in libertarian-minded New Hampshire!
Ron Paul is the only candidate who can beat Clinton in 2008, and he is the only candidate who can bring to the polls 10+ million of apathetic voters who hate politics and politicians, who haven't voted in years, and who only want the Federal Government to protect the borders, guard the coasts and the airspace, and aside from that just to leave them alone!