the sound scientific approach is to said "i do not know if it exists or not, based on my current level of understanding", not dismiss it entirely. the foundation of science is to admit we do not know and go about discovering it.
This is the kind of reasoning I hear from alien hunters, crypto-zoologists, and young-earth creationists. They would all have us believe that something is reasonably viable until it has been completely disproved. It's perfectly reasonable to believe aliens built the pyramids until we have scoured every corner of the universe and proven that there are no aliens. Bigfoot is as likely as not to be real until we have mapped every inch of wilderness on earth. Evolution is "just a theory" on equal footing with "intelligent design" until we can go back in time and document speciation. That's not how science works. Until there is evidence for something, there is no reason to believe it and no need to disprove it.