There are three basic reasons to be skeptical about the validity and accuracy of polls: First, there is the well-known problem of bias that results from how polls are worded. Second, the raw data for the polls almost always is "adjusted" by the pollsters to give more weight to the Democratic responses. And third, the results of the polls almost always are within the reported "margin of error." So one can not always be sure of just exactly what polls are saying.
Of course the usual suspects will always tell you that their polls showing their messiah in the lead are always 100% correct.
Thanks to our friends at American Thinker