Yes, the Stratemeyer Syndicate used ghostwriters, but a lot of them were the same person anyway, Leslie McFarlane being the most notable for the Hardy's.

And given the extent of some of the perils the boys find themselves in (knocked out, drugged, tied up, gagged, tied to harbour supports to drown with the rising tide, nearly blown up, hogtied by an evil rodeo clown, to name but a few) you must have been one REALLY jaded 9 year old! ;)