This is so easily misunderstood. If you review the statements throughout Shas on ?? ??? ????, you will discover that it is misinterpreted by people way too often. If you are made aware of an allegation that something occurred, there is no reason to disbelieve that it happened. That would be foolish. Should one not trust just because the material is negative? Rather, it means that there may be alternative explanations, and that one should be ready to accept those as the reasons for a reported behavior.
The obvious difference is when there is no alternative explanation that matters. A case in point that is tragically more common than we would hope. There is a story reported that an individual (let’s call him Joe) abused a child (let’s call him Jake). You, the listener to this, may opt to distrust the information, but this has nothing whatsoever to do with being ?? ??? ????. If you otherwise trust the one giving over the information, you might seek another explanation for what occurred. In this instance, it is quite difficult to excuse the behavior, as the circumstances, even the intention of Joe, would not diminish the victimization. Invoking ?? ??? ???? could well be a huge mistake. It violates the fundamental requirement of ???? ??? ????, and trashes the virtue of ??? that is basic to being a Torah Jew. I’m sorry for using this example, but it is one that becomes central discussion too often, and is a perversion of the intent of Chazal.