Most of the time we aren't faking the information but succumb to natural biases and thus disregard evidence to the contrary. This isn't restricted to climate science; it's more like a general rule of thumb for all the science (hence The Linguistic Wars, Susskind vs. Hawking, embodied cognition, the multitude of interpretations of quantum mechanics, the continued existence of null hypothesis significance testing in the face of some ~80 years of research demonstrating it's fundamental problems and no empirical or theoretical evidence to defend it, etc.). The positions that the public hears aren't as representative as they would seem- a small connection of "big name" scientists tend to influence material designed for public conception. This is as true of the "deniers" or "skeptics" as it is those involved in the CRU emails.
Far more importantly, climate scientists (like scientists in general) speak one way when they address colleagues and another in addresses to the public. The research doesn't reflect the certainty of this too oft repeated 95% (or 98%) opinion among scientists that "global warming" or "climate change" (which, for simplicity, we will define as described in IPCC summaries) is correct. Certainly, most climate scientists think that the observed warming is due largely to human activities. But even those who think the IPCC summary version correct are generally far from thinking that their position is sufficiently supported by the research. Rather, they acknowledge widespread problems in the accuracy of models, capacity to deal with enormously complex and interacting systems, failures in predictions, numerous postulated climate drivers that could account for substantial amounts of warming attributed to humans, etc. However, they also know that the public tends to misunderstand the ways scientific research and progress work, and that, especially in politically or otherwise sensitive issues various persons or media are wont to take indications of doubt or alternative explanations and make them into something they are not. So not only do they essentially lie to the public, there are recorded seminars/conferences you can watch in which climate scientists discuss how to lie to the public (not that they use the word lie, or that they lie to cover anything up rather than because telling the truth would result in misunderstandings that are more distorted and inaccurate than the lies).