I think the truth of the matter is that people tend to believe what they want to believe. It doesn't really matter which side of an issue they may prefer. In my experience, the true disbelievers - I define to be those who are predisposed to an authoritarian view of the world and who desperately need to believe that they understand the world completely - are just as bad as the true believers. I think they are two sides of the same coin because they both become irrational or unreasonable when their beliefs are challenged.
True disbelievers prefer to either attack the people making claims, misrepresent their claims, or address only the trivial or obvious cases, rather than addressing the interesting claims in a reaonable manner. The favorite trick is to trivialize the facts. Worst of all, they will deny any evidence that goes against their view, but readily accept any so-called skeptical argument with no proof whatsoever! The true believers cry foul when presented with evidence that contradicts their beliefs. They will deny, obfuscate, and redirect the discussion, rather than facing the facts.
In both cases, when on the losing side of an argument, they will disappear, only to appear later making the same argument in a different thread.
Imo, the sad thing is that interesting claims are often all but lost because they get tagged with a label. Crop circles are a good example. There almost certainly are crop circles that occur due to some natural phenomenon. It may be due to something as mundane as wind vortices, but there is some published physical evidence that there could be something more interesting in some cases [there is a fair amount of anecdotal evidence supporting this notion as well]. However, because the claim was associated the notion of visiting aliens and the fantastic designs that appear from time to time, all crop circle claims get lumped into the same garbage heap.
Ball lightning and earthquake lights were once victims of association as well. Part of the reason for this, I think, is that many people fail to separate the actual claim, from the interpretation of events according to the witness. While a person may in fact have witnessed something unusual, their interpretation of what they saw could be completely wrong. The claim is then rejected based on the interpretation of events, rather than the reported events themselves. Once the skeptic has decided that Bubba didn't see ET [which was decided long before Bubba walked into the room anyway], he or she assumes that the entire report is useless, when it still might be quite intriguing given the proper frame.