Hi Clive,
...who actually dare to SAIL in salt water? (grin)
Having said that, if I were considering the purchase of two roughly equivalent boats - one that had lived in salt, and the other in fresh - I'd take the lake boat, hands down... But, as Braden mentions above, you might be needlessly disqualifying a potential great boat taking such a myopic approach...
Good luck, and best regards,
Jon