When watching a show a while after it's released you can sometimes tell when a show was canceled because a season will end on a big (occasionally spiteful) event.
The following season after it's picked back up occasionally stumbles a bit but I'm wondering what examples can you think of that were especially bad?
Veronica Mars. Incredible first season followed by 2 lesser but still good seasons. They made an incredible kickstarter video for a revival movie that I believe was the biggest kickstarter ever at the time. But the movie was really bad. There was another Hulu season after that I can barely remember watching except for the awful ending.
Some things should just stay dead.