I personally haven't collected souvenir spoons or dealt with that end of collectibles. Is it better to clean them up or let them be. Found a whole Ziploc bag with over 50 at my in-laws. 90% are in great shape being silver plated or sterling - while others are unknown metals. (John F. Kennedy silver and other presidential spoons, Tony the Tiger by Wm Rogers, Worlds Fairs, many states, etc) Any help appreciated!