This is a tricky one. Though Richard Doty is a legend in UFO circles, he qualifies as a “loon” only under the satisfaction of certain conditions, the main one being “Doty is not a cynical liar”, that we are not entirely sure he satisfies. Doty is the main, uh, witness of Project Serpo, a science fiction story presented as fact on several web forums in November 2005, quickly convincing numerous UFO “researchers” such as Bill Ryan, Kerry Cassidy, Linda Moulton Howe and Len Kasten (who even wrote a book about it) about his claims (they didn't need much prompting).
The basic idea is that Serpo is a planet of the binary star system Zeta Reticuli, 39 light years from Earth, with a breathable atmosphere, populated by an extraterrestrial race known as Ebens – short, brown, village-dwelling creatures of which there are some 650,000. One such was a survivor of the infamous 1947 flying saucer crash at Corona, New Mexico, and the American military, by reverse-engineering the spacecraft, has since sent missions to Serpo (excerpts here), missions they are (but of course) covering up. No, it doesn’t add up, but who cares? The UFO community certainly doesn’t. In any case, the story was spread in 2005 through an e-mail from “Request Anonymous” to a Ufology mailing list. “Anonymous” claimed to be a retired US Government official with top-secret clearance, and was only later revealed to be Richard C. Doty, a former security guard with the Air Force Office of Special Investigations. Doty, interestingly, had a book to sell (The Black World of UFOs: Exempt from Disclosure, coauthored with Robert Collins), and the surge of interest in the story coincided nicely with the release of that book. One can't but admire the marketing strategy.
Doty has later claimed that he was tasked with hoaxing documents and feeding false information to UFO researchers, a claim that seems to have put off the UFO communities (on the one hand it reaffirms their conspiracy theories; on the other it suggests that many of their cherished UFO delusions may be false).
Diagnosis: Hard to tell, really, but serious delusions and clever marketing ploys are not mutually exclusive. It is also a bit early to tell how his efforts have affected the UFO communities, but they are unlikely to have made them into better critical thinkers.