Found this very interesting blog post that differentiates skepticism/doubt from denialism:
The writer contends that the AGW denialist movement is "a most distinctly unskeptical movement." In the following quote, the writer distinguishes between skpetics and cranks:
"Scientific skepticism looks at the totality of evidence and evaluates each piece of it for its quality. Cranks are very selective about the data they choose to present, often vastly overselling its quality and vastly exaggerating flaws in current theory, in turn vastly overestimating their own knowledge of a subject and underestimating that of experts. This is perhaps the key characteristic of cranks and the biggest difference between a crank and a true skeptic. In addition, because the mainstream rejects them, there is often a strong sense of being underappreciated, leading them to view their failure to persuade the mainstream of the correctness of their views as being due to conspiracies or money. Antivaccinationists, for example, view the rejection of their belief that mercury in vaccines or even vaccines themselves cause autism by mainstream medicine as evidence that we're all in the pocket of big pharma. Global warming denialists see the consensus as being politically motivated by the desire of "liberals" to tell them how to live. [my emphasis] Evolution deniers view evolution as the result of atheistic scientists wanting to deny God. People like Sandy Szwarc view the consensus that obesity leads to health problems as being due more to moralizing and bigotry against the obese, which, whether it is true or not, is an easy claim to make because there has been and is a lot of bigotry against the obese."
The point here is that cranks/denialists have an agenda. I believe (as per the sentence I highlighted) that global warming denialists are coming from a political P.O.V.(e.g., liberatarian, like Penn Jillette who is mentioned in the blog post) that sees AGW as part of a vast left-wing conspiracy aimed at controlling people's lives. So, an AGW denialist (as opposed to a skeptic or doubter) will not truly be able to evaluate the science because unless they are aware of the political bias they bring to the table. And, yes, the so-called "eco-religious" also bring their biases to the table as well.