Cletus, mind if we have a quick, public messaging discussion? We're going to be called cranks, and many people are going to be very, very sympathetic to that, so we need to avoid sounding crank-like. Yes, everybody has an agenda, but pointing that out only makes us sound like cranks so we probably shouldn't do it. Besides, it is essentially ad hominem and ad hominem is both invalid in general and stupid tactically, because comparing the men at issue will come down to "respected scientist" versus "guy on Internet" and we'll always lose that comparison.
Instead, we should criticize ideas, not people, and point to favorable facts. For example, you could suggest that the Mars example is disanalgous in at least two respects: one, the Mars example involves an honest error rather than actual attempt to defraud, two, the interesting debate in global warming isn't on prospective measurements (which we can do accurately, like you can accurately measure the topology of Mars) but on whether we are drawing the right conclusions from data which has been sliced, diced, and remixed from an error-filled patchwork collection of proxies such as, e.g., a few dozens specimens of a particular type of tree in Russia taken in the 1970s which people believe accurately measure the global climate in 1400 AD.
Check that last line out, incidentally: most listeners are going to perceive it to be mocking because it makes the enterprise sound like something which is being built on foundations of sand. However, it is very difficult to be called a crank for mockery of that nature, because to do that people would have to know paleoclimatology better than you do, and it would take an awfully dab hand at explanation to make paleoclimatology sound like something other than a bad joke.