Or more politely put, have large error bars. Those error bars are significantly larger than the margin. Those error bars are so wide, and so correlated, that

Or more politely put, have large error bars. Those error bars are significantly larger than the margin. Those error bars are so wide, and so correlated, that the chance of what seems like a blowout for one side or another is actually fairly high. (40% according to Nate Silver, where blowout is defined as one person winning all 7 swing states).