Note that I did say "mostly self-moderating." If there's an individual (or a few) whose behaviour leaves a bad taste, and those individuals are clearly ignored by other regulars, anyone who is coming into the group and lurk for a while will soon see which posters provide the quality content.
In some cases that will affect only whose advice they might follow, but in other cases it affects whose services they might hire. That easily becomes incentive for self-moderation.
I mean it in a broader sense than that: the culture of the group as a whole will settle into a state that is for the most part representative of the personalities which are found there (or at least the perception of those personalities that they present).
Read alt.os.linux.slackware for a few weeks if you're curious as to what can happen if the group is generally left to take its course. You might find the archives of the past year or two to be of particular interest, in examining how that group adjusts to "brief disturbances of its calm meditative state, as the pebble disturbs the stillness of the pond ..." (bonus points if you recognize the reference! :-)
That group has a number of regular posters, most of whom can be very helpful, though some may be perhaps opinionated, and none of whose intelligence or general knowledge of the topic can reasonably be brought into question. There are also some regulars whose contributions are more in the form of intelligent questions and an eagerness to learn.
There are also a small number of (for lack of any better term) net "kooks" on that group. Some show up only periodically and it doesn't take long before their colours show through whatever false front they resurfaced with, while others (one in particular) are completely unrelenting and obsessed.
Most of the others have long ago decided that they have much better things to do than to try and teach these social misfits how to fit into the "society" of the newsgroup. No one entering the group and reading their messages for the first time takes them seriously for very long.
It doesn't have to be that way. If there's only one "miscreant", let that person be perceived as they are presenting themselves. There isn't any reason to be dragged into the same place. If their message leave a bad taste in your experience, simply killfile their messages, ignore followups to them, and get on with the better things in your life.
I've seen that tried, and have yet to see it work. The best examples I can think of, among the newsgroups I read regularly, are rec.audio.pro and alt.audio.pro.live-sound. Both groups have a core set of regulars that spend a not insignificant amount of time subduing, chastising, and making it evident to each other that each other's conduct is unfit for the group and the profession.
I find both groups to be mostly unusable for serious information gathering because the "signal-to-noise ratio" just isn't high enough.
Contrast that with the alt.os.linux.slackware group, where the truly obsessed are mostly ignored, and otherwise the less frequent "offenders" are reminded (not always "in kind" thankfully) what the newsgroup is really intended for. It certainly isn't the Eutopia of Netnews, but I'm sure you'll find that the signal-to-noise ratio in that group is quite relatively high, and consequently the group is very useful when looking for information.
Now, on that note, I seem to have had very good timing coming into this group. I've found the signal-to-noise ratio to be one of the best among the groups I read, and that I've been able to get great information from the group. :-)
I'm going to have to take your word for that, as I haven't been participating in the group myself for longer than a few weeks. However, if you have the time and the inclination, I'd be interested in knowing your reaction after reading the other newsgroups I mentioned above.
At times they're all chaotic, but overall, the most chaotic are those where it seems that what you're proposing is being attempted (I might have said "exercised", but I doubt that the people involved are living up to what you would hope would happen here).
Does the newsgroup have a charter? If so, any conduct expectations should be laid out in the charter of the group, though even then, without moderation (which I'm not about to recommend) the only thing that anyone can do is to point an offender to the (periodically posted) charter, and to ignore a repeat offendor.
Any new agreements that are reached among the regulars of the group should be ammended to any existing charter. If there is no such charter, it might be worthwhile to draft one, and to gain support from the group membership to have it adopted as the group's charter.
Failing that, you can only count on people's desires to present a professional, knowledgeable image of themselves (which, frankly, should be incentive enough for the participants to maintain control of their behaviour).
No one has to take the bait if he does continue "it". If no one does, no chaos can ensue.
I do hope that you have the time to review the alt.os.linux.slackware archives. I'll be surprised if you have time to review it far enough and thoroughly enough to follow all the history that group has (in fact, I'm sure you'll find it to be mostly a waste of time unless you have personal interest in Slackware Linux yourself), but your statement above reminds me of one of the "periodic" types I mentioned above.
In that case, it became apparent the individual involved seems to have "other" motives for attempting to clean up the chaotic behaviour in the group, which I'm not suggesting is the case here, but rather that you should keep in mind that it may begin to appear that way to others.
I would disagree, from my experience on other newsgroups. What I've seen suggests that chaos ensues when someone attempts to "correct" someone else's behaviour, but if no one says anything at all about it, it's left with just one (or a small number of) poster(s) providing a very clear, very unprofessional and not credible image of themselves.
Not even that. We need to not let newsgroup matters become personal.
If I disagree with something you say (or anyone else), it's up to me to point out my disagreement in such a way that does not turn the discussion into a personal attack. If I can't do that, then my disagreement isn't going to be very credible, and it will become obvious if I have to resort to personal attacks just to try and "be heard" above logic and reasoning.
Now that's a lot to say for someone who has come into the group only a small number of weeks ago and not researched the archives for the type of traffic that you're hoping to eliminate. However, I feel quite confident that the experience I lack in this group in particular, I generally make up for in other groups which may be of different topics, but have plenty in common with the nature and intent of alt.security.alarms. I hope you will consider what I've written.