You know there are promoters of psychic phenomena who say “we realize that many psychics are fake or simply deluded, but what if only one of them is actually psychic?”
As with anything else, let’s see the evidence, if any are real. Sure, just because 99% of them are fake, it doesn’t absolutely mean that the other 1% are as well, but it certainly doesn’t help your case.
That’s the same exact thing that psychic promoters say.
So here’s something reasonably scientific to say about extra-terrestrial life:
"While we don’t know the details of how life formed on this planet, we do have some good guesses about the generalities, and given that there now seem to be lots of other planets out there in the universe, it seems likely that other planets somewhere else would have life also.
"However, there probably were conditions on the Earth that made it more favorable for life: the temperature range being right for liquid water, an abundance of carbon, oxygen, and other elements, etc. These would tend to make us think that the vast majority of stars wouldn’t have planets with conditions this favorable, so the chance of intelligent life being anywhere that we could reach it is vanishingly small. Hell, the chance of life being close enough that we could even detect it seems really really small.
"Given the enormous distances, and that we’re pretty sure about that speed of light thing, we can imagine what it would take for our civilization to go out and visit other worlds to look for life, and it’s just not plausible at all. Other civilizations would have the same barriers in looking for us.
"Therefore the idea that we’ve been visited by alien life, here on Earth, is really outlandishly unlikely. We’d love to know that it happened, but we’d need very solid evidence of it. And if it were happening, we think that solid evidence of it should be very easy to obtain.
“Since the little evidence that we do have is so easily attributable to mistakes, fraud, and delusion, it does not come anywhere near being convincing. The only reasonable tentative conclusion is that ALL those reports are wrong. However if we’re wrong we’re certainly willing to have a look and change our minds!”