I wouldnt think twice about buying a soaked card, a good % of PreWar baseball cards and almost all Victorian Trade Cards have been soaked. If not you would see way more back damage. The kids in 1880 didnt have toploaders or binders full of plastic pages to store and display, they had Flour Paste and Trade Card Albums or old Ledgers.
Get off the "Value" trip, its eye appeal, many cards are collected for the enjoyment of the history of the game and the challenge of set collecting.
Value is secondary, some of my favorite PreWar cards/sets have little value
