As one of the world's most notorious 'UFO debunkers', I have a much more sympathetic assessment of the body of reports -- and their reporters -- than you seem to have!

I've found mental problems to be really rare -- crazy people talk with Jesus much more frequently than space aliens. Ditto hoaxes, although there have been some spectacular photographic ones -- more common are pranks, in which somebody plays a cruel (if delicious) joke on innocent percipients by staging an unusual visual phenomenon -- such as candle-bags or my favorite, a kite carrying a flare.

The reports I see are overwhelmingly due to innocent misinterpetations of visual stimuli, often accentuated by coincidences. Often the stimuli is 'ordinary', if unfamiliar to the percipient -- but in a large number of cases the stimuli is 'unsolvable' because those responsible for it (military activities, illegal activities, etc.) make efforts to elude detection and post-hoc verification.

Sincerity of the percipient's belief is no measure of accuracy. And the evidential value of the story rots from the very start -- it goes bad with time, with every retelling, and particularly when muddled by investigators asking leading questions or seeking to mold the perception/memory into a favored hypothesis.

Behind all of this 'noise', is it plausible that there's an ETI 'signal' for which no earthly explanation is possible? It's certainly not DISprovable, but my own investigations have persuaded me that it is not NECESSARY in order to develop a hypothesis to account for the process of forming ALL eyewitness UFO reports -- even those which are simply unsolvable due to our human limitations.

See www.jamesoberg.com's section on 'Space Folklore' for elaboration and some very amusing world-wide reports that were traceable to secret Soviet space activities.