Hi Jeremy,
It's a rare yacht that doesn't ever get any water in the bilge - the simple process of withdrawing the log transducer to clean it inevitably admits sufficient seawater to get carbon teel keel studs, nuts and backing plates rusting. Nearly all modern yachts use type 316 austenitic stainless for this purpose in order to avoid the rust problem, but Moody went for carbon steel, principally because of concerns about crevice corrosion in austenitic steels, a process which was not well understood when Marine Projects started building yachts and, as far as I know they stuck with tis until Moody shut down and sold their brand to Hanse.
Other sources of water are leaky windows / hatches, leaky domestic water systems, leaks on the engine (raw water pump gland is not at all unusual), leaky stern gland, etc. While all of these are defects, which can and should be repaired in the fulness of time, none is a serious defect and you should not expect brand new perfection in a thirty odd year old boat - think of buying a thirty year old car.
Of course, some owners are fanatical about caring for their boats, but most do what is necessary to stay safe and go sailing.
Peter