WangGuard is the best plugin I have found to altogether eliminate spammers and sploggers from your WordPress and BuddyPress site. I have created and manage multiple blog and community sites. Since installing the WangGuard plugin I have had 0 problems with my sites. Most of the annoying spammers I do not even see, WangGuard blocks them from even being able to join my sites!!!
In the rare occasion that one does slip through, that entity is eliminated from my site with the single push of a button and all their posts go poof too.
If you run a MultiBlog website, you can easily install WangGuard for your members to use. Any group administrator has the power to submit spammers. Users do not have that power unless you let them. Do not worry, they cannot ban people from your website. It sends a request to you and you decide for yourself.
The WangGuard plugin frees up a huge amount of time for you to do more useful things to your website instead of spending all day running around putting out fires.