Mostly no. Think about it: polling companies are paid to be right. A biased company that produces inaccurate polls is not going to be in business for long. That said, some firms do polling with less rigorous methods than others. For instance, Rasmussen is an automated poll that only calls landlines. Its sample therefore excludes people with cell phones as their primary phone - and that's typically younger people. Older people tend to be more conservative and more Republican, hence the well known GOP bias in Rasmussen's results If you really want to get into the weeds of polling strategies and methods I recommend WWW.fivethirtyeight.com, Nate Silver's uber-wonky poll ...