so it is consistent with their internal, subjective universe. Even if these are just con men, they are still trying to construct a believable, consistent reality for the benefit of their marks. They may not believe it themselves, but it has to be convincing for their victims.

Permit yourself a little Gedankenexperiment. Lets assume, just for the purposes of argument, that one of those image artifacts actually was a real UFO, a part of some Martian welcoming committee trying to discreetly check out this strange new visitor. Wouldn't we, as skeptics, make every effort to rule out any evidence that didn't support our own predilections? We would be willing to go to extraordinary lengths to rule out any evidence those were real UFOs. And we would have all sorts of perfectly reasonable opinions that would tend to distract us from the truth.

The universe is fuzzy, not sharply in focus. Our perception of it is fuzzier still. There is plenty of room for both lies and the truth to hide, or to masquerade as something else. Gathering data and basing conclusions is not a cause-and-effect phenomenon, it is actually statistical, and it is a matter of consensus and reflecting of the contemporary Weltanschaung. Remember the Martian Canals? Don't you believe yourself anthropogenic global warming opinions are biased, even when held by experts? I really can't dispute that assertion either, I can only make statistical judgements and rely on Delphic authorities, even if I concede they have been wrong in the past.

We know those are not UFOs because we know what image artifacts look like, and we know anomaly peddlers lie through their teeth because it is in their financial interest to do so. That skews the statistics in our (the skeptics) favor. But it is not conclusive evidence. We know we can't trust people who are only in it for the money. We also know some honest people really WANT to believe, and that will inflence their critical judgement. They will also not be aware they are so influenced, they will marvel at our closed-mindedness and stifling orthodoxy.

When we say "those are not UFOs, they are ordinary flaws in images" we do so with a high probability of being right, but not with any true certainty. Whether we like it or not, the truth is a publicly held opinion, not a physical fact. Physical facts can only be determined by subjective observations and they can only be interpreted with subjective reason.

That's right. The truth may be objective, but perception and reason are BY DEFINITION, subjective.