scotch lad,
i feel i must put you right on a few point. hubs are removed and not blown out as you suggest. they are removed to inspect the brake linings, check the hubs for overheating ridges or damage, everything is cleaned with brake cleaner and the shoes roughed with emery cloth, the adjuster/compensator is checked for operation and a smear of copper slip if required, the hub seals and bearings are also inspected and tested and the retainer springs are inspected and check for correct location.
and when during a car service is the clutch, gearbox, diffs, alternator, starter motor etc removed to see if working correctly? do they not report a problem and charge additionally for any remidial work? in this respect we offer the same level of service for a caravan as any car