You can find Gallery Checker in Rotation - Tube - Gallery Checker.
Every minute script checks Х (Amount of galleries to Check Per minute(!) ) from DB, note each minute, at each domain, so if you have 5 domains with SmartCJ - it will be for example 5 a minute * 5 domains = 25 galleries a minute.
Galleries are checked against `Galery Deletion Rules` , format 'domain|word' How it works: script checks html of gallery , looks for rules for this domain, and searches for 'word' in this html.
If script finds 'word', it deactivates gallery.
There's one method to prevent wrong deletions. For example, you add a rule with word 'test' and that site changed design and somehow added word 'test' at pages with working galleries. So 'Deletion Lock Stop Deletion if we delete more then X galleries in a row.' - if script deletes more then X IN ROW galleries from the same domain - it puts a lock on this domain and does not delete galleries from this domain anymore until you release the lock.
You can see locks at the same page Rotation - Tube - Gallery Checker.
Note, you can also delete galleries using Import Sets