Seemingly, everyone wants to put some mysterious entity behind everything they can't fathom. Soon thereafter, someone writes a book about the mystery, and even more people believe it. If there is research monies to be had, every people who know better jumps on the bandwagon. Global warming theories are the most recent examples, with UFOs and ETs not far behind.
Apparently, no one has every heard of a lenticular cloud. You quite often see them in the daylight, but sort of ignore them as funny looking clouds. Well, those clouds act like mirrors, as any decent pilot knows. They're sort of mirages in the sky. If the Brewster angle is just right, they reflect light from far away, and sometimes, hundreds of miles away. The effect has been describes many times, but folks apparently don't believe the scientists, preferring to believe the occult.
Lastly, I agree with Frank. If they were real, we'd have positive proof by now.