Re: waterlogged
I would think that water would have to get up over the stringers out of the bilge to damage the foam.In other words flood the floor and the engine if its an I/O..Hopefully the guy was smart enough to not let that happen.
Look in the bilge area for signs of mildew or black stains. Depends on how the boat is built also.Usually water logged foam is from letting one sit out in the rain and neglect..