Here's an interesting passage from that Des Moines Register piece Mike mentioned earlier--about Democrats bashing the Register's own poll. It's the part where the pollster defends her methodology:

J. Ann Selzer, whose firm Selzer and Co. contracts with the Register to conduct the poll, said that the percentage of independents surprised her.

But she said that she trusted the method she used in conducting the survey.

Selzer uses a random-dial method of reaching registered voters, then asks them if they plan to participate in the caucuses before asking them for their party affiliation.

"We went looking deep into these numbers to find ways that there was something else odd," Selzer said Tuesday. "I didn't have any other demographic abnormalities. Everything is exactly on track with what we've gotten before, with the exception that it's a higher independent."

As I said, I think there's reason for skepticism here. But you do see signs that she's onto something.

--Noam Scheiber