I think the admins do a pretty good job of cleaning up. They might take a day or two to respond during weekends, but let's face it, they have lives, family, jobs and other duties that interfere with their first love of moderating forums.
They also seem to have a tendency to stay out until they're asked in to do something about it. Frankly I appreciate that. Gives us a certain latitude to act like children, I mean ourselves! Round the clock surveillance is unsettling, and I think the boards would take on a very restricted feel.
OTOH I think moderators with certain restricted powers might also come in handy. Somebody that could prune out bad posts, but are unable to actually ban anyone, might have some merit. But who? My first thought is I wouldn't want volunteers, as they can get a bit "too" diligent. You can't force it on people, as they don't always give it their best effort. Nominated people that are voted in seems to be the best approach, but even that approach can have it's problems (can everyone spell "hanging chad"?).
No, I think in the end we just put up with a couple of days of bad posts on occasion. We (meaning ME!) need to learn how to deal with trolls better, and Rob is right. Removing their food source is the best way to deal with them. I've learned my lesson!