I've met Tom Snyder a couple of times - "call me Tommy" - and found him perfectly pleasant. My memory of watching him on his old show with Scarne was that he was respectful of John who was years past his prime.
There is a story about Blackstone Sr that well illustrates the concept of "working strong." Blackstone was hired to do a TV show with Milton Berle, then the biggest thing on television. Berle was notorious for crashing acts and making a general pest of himself at the expense of other performers. Old Man Blackstone had his own set of Big Brass Ones and was a very BIG star in his own right.
During the show, broadcast live, he brought Milton out and showed him a trunk. This had NOT happened in rehersal. Harry told Milton to get in the trunk and examine the bottom. He did. Blackstone dropped the lid, locked it, and said, "Now we'll get on with our show," and proceeded to perform with Mr. Television in a locked trunk on the stage. As the show was live, nothing could be done. When Blackstone finished, he let Milton out of the trunk. Berle knew he'd been bested by a master and let it go, but I don't think Blackstone was invited back.....
While I didn't see this happen, I did watch Harry Junior remind Milton of the story, which Berle remembered. He didn't say a word in complaint and spoke respectfully of Senior. As well he should have.
A few years ago there was a magic special out of a Los Angeles theater, hosted by Bill Shatner, Star Trek's answer to David Letterman, one of the world's great fatuous asses. Shatner was making endless smart alec comments during rehersal, always with the idea of putting himself in a "clever" position. It seemed that this would happen during the broadcast, with Shatner wandering from the script as it pleased him...for isn't the world all about HIM, or so he thinks.
Harry Jr put Shatner in his place by saying to him, "Nimoy was right. You DO overact!" Shatner was quite subdued when Harry performed.