I'm not discounting the account of people that say they have seen something that they are unable to comprehend or explain. But, it's a something completely different to jump to irrational conclusions about the nature or origin of that which you're unable to explain or comprehend.
When you attribute that which you cannot explain to higher powers i.e. aliens, god, angels, ghosts, etc. you are making claims that require proof and scientific evidence. Neither of those things are being offered in these cases. People are seeing what they can't explain by rational means and instantly jumping to these fantastical out of this world explanations. The more outrageous your claims are, the greater your burden of proof is. I have yet to see the burden of proof be met, by anyone. Not just in this thread, but anywhere I've looked. When the burden of proof is sufficiently met, I'll b the first to say I was wrong.