Freak asked me to implement your suggestions, as usual they are spot on.
And yes strict mode is enabled.

After doing so I checked the cp and had like 50+ forums.
Then I checked the forums table had 146 rows..
All the rows that were not displayed in the control panel had null values for forum_title and parent forum_id.
Plus the forum permissions and post tables had remaining rows with the bad forums.
So I edited the forums table to to add a forum-title and parent forum_id.
Then deleted them the normal way .
This cleaned them completely.

This was probably due to failed deletions over the years.

So I attempted to run the re builders and now have a error on rebuild posts.
I will post a new topic on that subject. with all the details.