protoboard, are you really asking “do they exist” or “have they visited Earth”? Those are two functionally different questions. Your post leads me to assume you’re really asking the second question.
I don’t doubt the substance of what you’re asserting here, except for the graped part. Why would an organism need such a thing as a coping mechanism for when it dies? How would such a thing evolve?
(I mean, I think it’s plausible that it’s an artefact of the system breaking down in a more or less repeatable way)
I thought I read somewhere that the vast majority of grey alien reports happened after ‘Close Encounters Of The Third Kind’ was released. Either that put the idea in people’s heads, or they all came here to see how they were portrayed.
In the same vein as this, I would assume that the logical progression of space exploration would be translatable to all manner of species. Meaning, before you can go into space yourself, you have to send other things into space to make sure you CAN go into space, then progress from there. If aliens did exist, why would they come here themselves to explore and therefore we have only seen aliens themselves. Why haven’t we seen any alien satellites? Recon drones? Observational machinery? I hold true to believe that our first encounter with aliens won’t be “little green men attacking the White House” but rather and announcement from NASA saying “something is coming our way, something handmade, and we didn’t make it”
I think the really important thing to understand here is that eyewitness testimony is not as reliable as people think it is. I don’ really have time right now to go digging up cites, but you can see how unreliable it is in a number of ways. For example, my wife did some police training as a volunteer and one of their tests for observation is not just to ask you what you saw, but to realize what you didn’t see. Most people, if they see A and they see C, then their brain fills in B, which they assume they must have also seen. They form “real” memories of B - by real I mean they don’t think they’re either lying, guessing or making stuff up - and are later surprised to learn that they never saw that at all.
If the eyewitness testimony is from a dream… well now we have an unreliable witness of a likely fictional event. I would say that finding anything true in a dream is an unlikely exception to the rule.
It’s so fucking big that* somewhere* there almost certainly are grey aliens. None are here on Earth, nor have they been recently.
I’ve never heard of his term before, “grey alien”, but if they do exist I suppose the only reason they would be grey is due to having to travel at the speed of light for however many years it is from their home universe.
What about the men in black they are more easier to find and try to understand than “grey aliens”?
I’ll go do a SD forum search 
Color is dependent upon light. If they travelled faster than light, their natural colors might still be catching up to them, making them look grey right now.
My not-too-serious take on ‘greys’ is that they are our earliest recollections as we emerged from the womb. Doctors and nurses in grey/green hospital garb, surgical masks that cover their features except for their eyes (accentuating their size too), and then lots of handling and probing and bright lights.
If that turns out to be the case I’m posting this to take credit.
Or they’re just rich kids from other planets messing with us. 
They’re enough of a “thing” that there’s a Wikipedia article, albeit one that “has multiple issues.”
I suppose one could say they exist as a psychological phenomenon.
Yet only 2 out of 10 angels believe in Americans.
Cite?
Elephants are pretty alien if you think about them for a bit. And they’re definitely gray.
Good point, but what if the alien is like a chameleon:
In that case the alien could be imitating a cloudy day that he arrived on earth, uh uh how about that theory?
Did Scott Baio give you pinkeye?
Eh, I’m sure I’m getting the details wrong somewhere. I was just going off a documentary I saw several years ago.
I think Ferret Herder response sounds more closely to what I was trying to remember. I’m not sure what the NDE connection was though.
And they were grey because 99 per cent of TVs were black and white, and most theatre movies were, too.
Anyway, some police-force cars were Nashes, so people believed anything.
Two dimensional electric beavers. They could slide along any flat surface. They could slide through the gap of a closed window.
I’m pretty sure they don’t exist.
All the ones I’ve met are green.