There has been much debate as to certain episodes of What's My Line being "lost". While it is true that the early episodes of WML and other kinescoped shows were destroyed, certain individual episodes being lost are due not to neglect but to "itchy fingers" or because of a special request.
Imagine an episode of The Honeymooners coming back after decades of being lost. That's what happened in 1985 when Jackie Gleason released the kinescoped sections of his variety show. There was great fanfare and ceremony. Gleason knew that he was dying and the money he would receive for his wife and family would take care of them for many years to come.
Gleason also said that he was going to release the 1966-1970 Honeymooners shows so that, in his words, "Those girls won't have to worry about anything". Wonderful thought but he passed away before a deal was made.
My point - Gleason saved everything. His shows and guest appearances, films, kines and videotapes; everything. My guess is that his vault has the lost episode of WML with him dressed as Ralph Kramden only nobody has bothered to check specifically for it. Jerry Lewis saved everything and so did Bob Hope. I'm betting Gleason's archive has it.
When you preserve your work, you want to preserve everything. Gleason was like a king at CBS and if he wanted a copy of himself on a show, he got it. It was those wishes that got him kines of all the shows from 1952-1957 which his company made a bundle in the 80's.
Remember the lost pilot of Lucy that was found under a bed by the actor who portrayed the clown in the episode. There are more kines out there that have yet to be discovered.