Theoretically, if you had perfect knowledge of reality, you could prove the existence of every thing that exists and discount the existence of every thing that you could not prove. The assumption is that you are human. Bat boy could live in the deepest part of the ocean where no man can journey. You could scour every square inch of the earth you can access and still not find him. Still he is not proven to not exist. He could be on another planet. Think of him as a metaphysical supposition.
To prove that one or two or a hundred incidences of the "tooth fairy" doing its thing are not in fact the tooth fairy does not prove that there is no tooth fairy. It merely proves that the tooth fairy was not the cause of those occurrences. The tooth fairy could very well be real and be exchanging cash for teeth elsewhere.
If something cannot be proven to exist, does that absolutely prove against it? The answer is "no."
The discussion isn't over whether or not bat boy exists. It's over whether or not he can be proven to not exist by absence of evidence in his favor.
Although, there is nothing to refute yet. One individual's anecdotal "evidence" is not going to convince a soul of anything. I could say that I saw a yellow pig flying across my backyard last thursday. The greatest logician/philosopher/scientist/whatever could not possibly prove my statement to be false. Nevertheless, it is hardly proven that it is true.
Some people seem to have the misconception that my objective is to simply disbelieve the supernatural how ever possible it may be. On the contrary, I am just not willing to believe in things unless there is suitable evidence to indicate their veracity in most cases.
So, anyone believe in the supernatural?