Absence Of Evidence IS Evidence Of Absence

"Absence of evidence, or the failure to observe evidence that favors a hypothesis, is evidence against that hypothesis. This is because we are significantly more likely not to see evidence for a hypothesis when it is false than not to see it when it's true — some assertions demand that the universe be screaming with supporting evidence, so when that evidence is not actually observed, it counts against it."

(NOTE:  This is true when an hypothesis has been thoroughly investigated)

If evidence is lacking when we expect it to be abundant, then it very much allows us to dismiss a hypothesis.