The honest and simplest answer for most people is "someone on the other side of an issue from me."

Still, there are people who seem to come from someplace where reality is optional. In a discussion on "anomalists" a few years back, I posted this analysis.

In this context, the thread on that photo from inside an airplane showing all the tanks and pipes is instructive. While Lindy had an agenda in posting it, and probably hasn't had her mind changed on it, she was willing to readily accept hard evidence that this particular item had no sinister function.

Same for the recent "lights in the sky" business. ARRELL linked to a guy who admitted launching balloons with flares on them. A more rational UFO enthusiast will discard this incident and head for the next one. A nut case will insist this guy with the balloons is really a government plant.

The line isn't clear, and moves around a lot, but I hope you get the general idea.