Actually, no. In most cases people around an abuser have seen questionable behavior or had concerns. People at Penn State in and in the community had suspicions about Jerry Sandusky for decades. The priest arrested for sexual abuse when I attended Catholic high school was considered a creeper by every single student and we all tried to stay away from him (the abuse was taking place with younger children in his parish). A list of priests credibly accused was just released in my diocese, I know of only one case that surprised anyone who knew these guys and even in that one, people in my parish where he was briefly assigned nodded their heads and said he was a bit too tactile with their kids.
Three teachers I worked with were accused of misconduct. One was turned over to the police and served jail time. All three interacted questionably with students. The one who went to jail had student taught with me. During that time, I had concerns about the way he interacted too closely with female students in particular. I talked to him about setting appropriate boundaries. His college supervisor talked to him. The male teacher who also was working with him talked to him. He was young--22 years old--and 16-18 year old girls found him attractive and were pushing the boundaries themselves which isn't actually unusual. In one case, a call was made to a girl's parent after she showed up at his residence under the guise of "trick or treating" on Halloween (small town means people know where everyone lives). This is not to blame victims--we discussed with him that he was the adult and it was his job to understand and set necessary boundaries with teenage girls who had crushes on him as that would happen for a few years at least.
Four years later, then employed at our school, he crossed the line with an 8th grader and he will never teach again. And at that time, two teachers had reported to admins that he seemed unusually close to more than one female student and perhaps grooming behavior was going on. (That the principal ignored those reports completely is another matter--but he is no longer a principal so there is that).
The other two teachers were both female (as were the accusers). Both of them spend social time off of school grounds with students, often one on one. In both cases, other staff members and parents were asking questions about this closeness with students. No one said they were so nice, so whatever and it wasn't in their DNA. We all shook our heads and said that something should have been done about them having dinner alone with students or meeting them for ice cream in the summer, etc...
Now, it could be that Delilah has no knowledge of grooming behaviors or never saw John interact with anyone in that way. But I would still dispute that no one ever says anything but that abusers were wonderful people.
Deepest condolences and sympathies to his family and loved ones. I can't imagine the hell they are going through. 
