Everyone always praises the old artists but what are the worst cartoons that those legends ever did?
For Gene Deitch in my opinion it's the Seeing Double from the Popeye TV show.
It makes zero sense and while the designs are alright and the backgrounds are decent it's just structured like they just slapped this episode together. There's even a scene where it looks like they cut something out and it becomes a completely different scene.
https://youtu.be/A4sHCZE09-A
It's like they rushed the entire episode, which they probably did. Even the Halas and Bachelor episodes Gene outsourced to the UK were more structurally in tact than this episode.