I don't know of any paid moderators of newsgroups and mailing lists on-line, though I'm sure some big bucks folks pay moderators of really huge groups.

But in the folk realm, it is usually volunteers who moderate, or the site owner. Once the on-topic issue is enshrined in the FAQ, along with expected behavior, it is extremely rare that there are problems. Most moderators are on cruise control, really. Only when really nasty stuff happens (ie hackers, spammers, etc), or technical problems arise (how do I unsubscribe sorts of questions) do they have to get involved. Other than that, all the moderated lists and newsgroups I've ever been in have been, the moderators are pretty transparent, and the job fairly simple once it is set up.

PS I hope the new filtering software does a better job than the above suggestion for filtering BS WYSIWYG suggests we use.