IIRC, Bert Convy or some celeb on Super Password said that celebs were tested prior to taping their shows. On the '70s Pyramid, announcer Bob Clayton mentioned several times during audience warmups that celebs came to the studio early on taping day to practice with old material, but they weren't tested in advance to the taping. This sometimes resulted in being stuck with a poor playing celeb for an entire taping day of five shows. Off hand, Jimmie Walker, Connie Francis, Paul Lynde and Mickey Rooney come to mind. IIRC, Walker and Francis never won a game the entire week they were on (no, they weren't on together).