You know, there was a time when the absence of hunger was what ruined a live television advertisement. In 1973, on The Tonight Show, Ed McMahon was doing a live ad for Alpo canned dog food, and they had a dog on the show to give the bowl of dog food to, but the dog didn't want any. Again and again he tried, but the dog wasn't interested. So, right as it was about to be a total loss, Johnny Carson jumped on the floor on all fours and pretended to be a dog and acted like he loved the dog food. And the crowd loved it. But it's stuff like this that made the live ad go away for the most part.
Here's the live Alpo ad from The Tonight Show:
Also, from what my father tells me, there was a Hall of Fame NFL player named Chuck Bednarick, who was hired as a color commentator on Philadelphia Eagles games, and the announcer asked: "Here Chuck, have a White Owl Cigar!" And Chuck said: "No thanks, those things make me sick." (White Owl Cigars was the sponsor.)