We sometimes see posts that contain just gibberish such as e.g.
From the variety of flags we receive it appears that the community is not sure what flags to use for these posts.
From network wide guides on flagging it is recommended to flag such posts as rude or abusive.
To make the best out of our anti-spam protection system please do not use the spam flag on these posts.
I quote from Shog9's post on Meta Stack Exchange: Why don't we treat rubbish the same as spam?
This is an utter waste of time. There is no meaning to the post! It's VLQ, it's abuse, it's Not An Answer, heck it might even be a spammer, testing the waters... There's no metric you can apply that'll narrow that down, because there is no meaningful content to apply metrics to.
So pick the flag that speaks to you. I'm partial to "rude or abusive", because enough of them immediately delete and lock the post, which is handy in those rare scenarios where someone's flooding the site with a lot of these... But VLQ or NAA work just as well in the vast majority of cases. The important thing to remember here is that when the post clearly means nothing, you shouldn't be wasting too much thought trying to decipher it; flag it and move on with your life.
Personally, I tend to use very low qualify flag. This should push the post to the low quality review queue where users can vote to remove it.
It gives the poster benefit of the doubt - if they really posted this just by mistake, this way of deletion does not come with the same penalties as having a post marked as rude/abusive. (Of course, downvotes and deletion still count towards the question/answer ban.)
AFAIR, I recently flagged such a post about one week ago, and I think I flagged it as "in need of moderator attention", because the other titles didn't match.
I don't see the content being rude or abusive. Of course one could argue, that that making such a post is abusive to the platform, but on this meta level, every flagging reason is meanwhile abusive to the platform, isn't it?
Well, the same fits to "in need of moderator intervention". Spam needs moderator attention as well, so does rudeness against other users.
But there is a box for freely formulating the reason, and I think I worte "for obvious reason" or something like that.
Spam would either need a link to a webpage or some kind of advertising for a product or service, imho.
The most positive assumption would be either, that a user was testing how the whole page works and couldn't delete his post, or somebody was logged in and had an accidental interaction with the keyboard (or his cat had) and didn't mention it. So I looked for reputation and user name, but these were not indicating such an accident.