So many characters in 1960s sitcoms had a Terrible Secret which, if uncovered and made public, would have Disastrous Consequences: loss of livelihood, loss of position, loss of acceptance in society.
Fortunately, no 1960s sitcom character was actually a card-carrying Communist. No, the secret was something less political: a witch, a genie, a martian, a talking horse, an angel, a ghost, a talking car, a robot. etc.
Above: Ray Walston in a publicity photo for My Favorite Martian (CBS, 1963-1966).