Re:
You mention TvF. I remember him from old USENET days, before he started to make bucks selling his views in books. Scientifically trained folks like him are a more difficult breed for us science hobbyists. There's enough detail and real science in his conjectures that makes it difficult to respond, unlike the Von Danikens. TvF is an unorthodox scientist who's major heresy from my view is that he selects the evidence that supports his hypothethes, ignores or trivializes the mountain of evidence against and stays married to his ideas, 'cause they're cool or radical. So, there are decided degrees of difficulty for laypersons in dealing with fringe science vs. outright psedoscience.
-philw