MathOverflow is one of the few sites in the Stack Exchange network where users with reputation 1 can post on meta.1 Clearly, this has some advantages2 and some disadvantages. Probably one of the disadvantages is that occasionally spammers can post here on meta.
Main question: To which extent should we consider spam posts on MathOverflow Meta a problem? Is this problem serious enough to reconsider whether the threshold for posting should be changed back to 5 reputation points?
1See the FAQ post: What are the reputation requirements for privileges on sites, and how do they differ per site? (current revision) - this is listed among "Site-specific changes". Related posts on this meta: Allow posting on meta without any reputation for the first week and Change reputation required to post on meta back to 5 reputation points.
2As indicated in the posts linked above, this was used by many users who needed to merge their MO and SE accounts when this site joined the network. Another possible case where this might be useful is when some organization wants to reach out officially (or semi-officially) to the MO community - they can post on meta without any additional barrier. (Perhaps this was somewhat in this direction - although in this case the user who posted the feedback from zbMATH already had sufficient reputation: Are there policies to respect in order for MathOverflow Q&As to be tracked back in relevant zbMATH Open reviews?)
My personal impression is that there was some increase in the number of spam posts on meta recently. (Of course, this might be skewed by the fact that there were several spam answers on meta during this month. Maybe this was just a random fluctuation.)
In a sense, there isn't much harm when a spammer posts a spam post here as a question - the question eventually gets removed and the frontpage is not changed at all. However, if spam is posted in an answer to an existing question, the question is bumped to the frontpage. (Of course, one could view this as a good thing - that some long forgotten question gets some additional attention after it is pushed among the posts with recent activity. But at least some of those posts don't really need renewed attention.) Regardless of that, even a spam question is a slight nuisance until it is deleted - but it seems that they are removed reasonably quickly.
In the previous post about this issue, there was no response from the mods - so I guess that the mods do not really consider this as a problem. Long time ago I asked Shog9 about this, the response was slightly reluctant: "Yeah; it's a trivial change, but unless y'all are getting a fair bit of noise there's probably no good reason to mess with it." (Of course, this was a long time ago - and one cannot draw too substantial conclusions from a single message. In any case, if some MO users consider this a problem, the first step would be trying to persuade the MO mods - which might not be easy.)
In case it is useful as a reminder, I'll add a link to this post: What should I do when I see a spam post on MO? (It works exactly the same on meta - enough spam flags remove the post and obfuscate the content even for the users who have sufficient reputation to see deleted posts.)
SEDE contains in the type Votes votes spam flags (VoteTypeId=12) and Offensive flags (VoteTypeId=4). I have collected at least some stats about spam posts. (In some of the queries you can change parameters if you want offensive rather than spam flags, or even both. The queries can be run on any site - I have linked this meta and in some cases main site.) SEDE is updated once a week - so the numbers below are from the last update.
- If we rely on the numbers from SEDE, we get 54 spam posts on meta - compared to 3227 spam posts on the main site.
- Among the spam posts on meta, we have 35 questions and 19 answers. Here are the questions which were bumped by spam answers. Four questions had two spam answers.
- List of posts which were flagged as spam - it is marked which of them were answers/questions.
- Longest time to delete spam/offensive posts
- Average time until a spam post was deleted: main, meta.
- Average is probably not a good measure - it might be skewed by a few exceptions. (For example, if some posts was flagged by mistake.) Median might be more suitable: main, meta. (At the moment, I got 28 minutes on main and 53 minutes on meta.)
- Number of spam posts on meta per month and per year
- Counts per year - including the number of questions and the number of answers.
- Percentage of spam posts among all posts on meta and on the main site. (Thanks to rene for help with these queries.)
For deleted posts, we can't get data about the OP from SEDE - so in this way we won't get some information how many of those posts were posted by a user with reputation one. (But my recollection is that this is usually the case. At least if I look back on my spam flags, I can see there only users with reputation 1 and accounts that have been deleted since the posts.)