What these guys fail to acknowledge is that - I am in a discussion about this in another context overnight - 10s of 1000s of testimonies, memoirs, interrogations, taped interviews, and other statements, not just one or five, exist in various archives and libraries. And that it is to be expected that some are, being charitable, just not right. Without doubt, some will be fraudulent, some will be all mixed up, some will be crankery.
These 10s of 1000s of retrospective statements of various types from different individuals exist along documents, diaries, press articles, appointment books, memos, reports, forensic evidence, etc.
The way to figure out which few are "not right," unfortunately, is do the hard work of reading many, many sources out of all this material; comparing them; thinking about them; and making decisions about how they fit together, if they do, and what they demonstrate. That is what historians, which Clayton admittedly is not good at being, do. For example, that is what Nick Terry does. Mostly, historians use all this material to work out the history - not to expose cranks and charlatans.
Clayton's hyperventilation on this topic is only somewhat amusing. It would be as though someone denounced every historian of the American war against Vietnam for not being on the TV talk shows and all over the Web deconstructing and exposing the fake veterans and their false stories. In the real world, the question would be, "And why should they do that, when they are busy with the '10s of 1000s' of documents, newspaper articles, statements, etc.?" But Clayton sees no value in spending effort to get the history right, so to speak, and as he says lacks the proper skills to do so.