Today's inspiration is a nice piece from the Friendly Atheist about how abusers can manipulate church groups into taking their side and neglecting their victims.
Really, though, it's not just churches that have a problem with this. There are a lot of news stories of horrific crimes that feature friends and family of the culprit talking about how they were such a good person, and they can't believe that the culprit could possibly have done something like this. A lot of the rest feature people that were obviously kind of strange, but still not to the point that everyone around them took decisive action. (To be fair, the examples where something useful is done tend not to make the news as easily. It'd probably be interesting to try and analyze how often something slips past everyone versus how often things get caught, but I have no idea how one would even start to work on that.)
It seems that in real life it's a lot harder to detect evil than one might think. It's enough to make me decline to put that much stock in character references, particularly when they're used to question whether someone actually did hurt or insult someone else.
I think it's worth remembering for anyone that people can be more complicated than just how they act around you; just because you've never seen them act a different way isn't sufficient to prove that they never will or that they never have. That doesn't mean we have to automatically assume everyone around us is hiding some secret evil, and if someone has held to a given pattern of behavior around you, it's fair to trust that they will continue to do so. But if someone else says they act differently in other environments and around other people, your experience alone isn't sufficient to prove that accusation false.