@SpreadsheetSnorlax asks
found some possibly fake cards in a donation pile. Okay to leave them since they're free?
Jeff answers
I'd separate them until identified. Free cards can still confuse new collectors or enter later trades as genuine. If something is confirmed unofficial and appropriate to keep as a novelty, label it clearly and keep it out of ordinary trading stock. Generosity works better with accurate information.
— Jeff, infinitepulls.com