why it's not classified as spam.
This is part of the external algorithm, thus, I cannot answer this question.
I know, I know. It was only a rhetorical question.
Do you know the situation in case of Bad Behavior?
Do you have the impression that it improves the spam prevention rate?
No, because postings that contain words, which are flagged as bad words, are blockt and not marked as spam.
Yes. Without a counter you'll never know, if the bad words and the IP filter works.
That's an intentionally good idea. But that means to open (parts of) the admin area to the moderators, which is actually not the case.
...and maybe, we have more problems as before in case of false-positives.
Well, it's always possible to abuse the given power as a moderator or simply to make errors. It's as well possible to overtune an automatism. In both cases false positives will occure. Nothing we or someone else could prevent.
When I was a operator of a big forum with many users and many postings per day or week, I would wish to split the work between me and a trustworthy moderator or, in a really big forum, a team of moderators. Therefore I have to give away parts of my authority. The question is, how far to go.
As a moderator here in this forum I collected experiences and my conclusion is, that I as a moderator can not access all functions I think I need. I think it would be useful to give moderators access to the blocklists (reading, writing (but not deleting datasets)). That would need a new structure with one row per bad word/IP and (IMHO) an additional column for the user name of the inserting user and (maybe) a datetime field.
Additionally I tend to add a mark-as-spam- button/-link to the options for admins and moderators in the side bar. It is annoying for me to have to open an obvious spam posting (with loading images etc.) to report it as spam and to remove it.
Trenne niemals Müll, denn er hat nur eine Silbe!