I don’t think people in glass houses should be throwing stones, as Nate Silver is here. His predictions were pretty off. He had a 2.9% bias in favor of House Democrats in his predictions.
This.
Silver is a leftist with an agenda. Rasmussen's polls were fairly consistent with most public polling, including those of SurveyUSA, who Silver praises. Accusations of bias are ridiculous and his method of poll evaluation is poor.
Polls are a snapshot of public opinion at a point in time for the population surveyed, and should be evaluated as such.