Almost nobody ever looks in a church window and sees what happens in a service.
I’m surprised to hear that the J-dubs don’t have a ready answer to this question, but I think the vandalism theory makes perfect sense. In the old days they made a lot of enemies with their obnoxious witnessing methods, not to mention their unorthodox teachings–so the JWs have a persecution mentality based on hard evidence. Remember, it isn’t paranoia if they really are out to get you.
Somebody turned the outfit around and now the witnesses are taught to be nice when going door-to-door, so the old antagonism has faded radically. I’d suppose that their persecution has been reduced by 90% compared to seventy years ago
Part of that might be the climate of this age. Nobody believes much of anything any more, and they don’t care much about the few things they do believe. So nobody cares what the J-dubs believe. “Eh, whatever…”