Aha so I was wrong, Akismet wouldn’t help you in this case.
Sorry @kirupa, this isn’t on our roadmap for the forseeable future, as we don’t have (any, that I can receall) paying customers complaining about it. On top of that, I think ghost bumps are correct and proper as they highlight problem topics that tend to attract spam. You could sponsor someone in #marketplace to work on it if you wish.