BPers in particular often have a God-like faith that science is impartial and neutral. As an actual scientist I have often said that is not true at all, and the response is "then you're not a real scientist, man, you non-believing heathen!". Anyway, here is some proof to back up my claim, and it's worth noting that this is from another real scientist rather than some crackpot 14 year old on the internet.

University of Pennsylvania marketing professor J. Scott Armstrong conducted a meta-analysis of all studies of peer review conducted since (and including) Abramowitz’s, to determine whether there was, in fact, a systemic problem. He concluded that the peer-review system was highly unfair and discouraged innovation. Part of the reason stemmed from known bias: papers from more famous institutions, for instance, were judged more favorably than those from unknown ones, and those authored by men were viewed more favorably than those by women if the reviewers were male, and vice versa. But others had to do with the less visible bias of belief—the type of bias implied in Haidt’s argument and Duarte’s methodological concerns. “Findings that conflict with current beliefs are often judged to have deficits,” Armstrong wrote. Here, the question isn’t about things that can be easily tested as empirical fact, like whether the sky is green or whether French fries make you skinny. They’re about the nebulous areas of philosophical and ideological leanings about the way the world should be.

In many fields of science - especially the softer ones - there is an "establishment". If your research goes against the beliefs or self-interest of the establishment, then you will find yourself unpublishable real quick.

http://www.newyorker.com/science/maria-konnikova/social-psychology-biased-republicans

Edit: before anyone says "that's only one paper man, and it's flawed!" read the article. There are quite a few papers that are linked which all expose some type of bias in the peer review system.