I completely understand where you are coming from.
I have a few hubs where I would look at the ads and some would be quite provocative, and not something I want my viewers to be looking at. Some of my viewers can be quite young because a lot of my hubs are about games, and I have seen these ads on those hubs.
I currently do not know of a way to do this, or if its even possible. I will keep an eye out and let you know anything if I find out.