#2: CatDog
CatDog is another nostalgic Nickelodeon cartoon that aired from 1998 to 2005. It follows the everyday antics of a cat and a dog, who happen to be conjoined siblings. Just from this description of the show, you can probably tell why it was questionable for kids, at best.
As you can imagine, being a conjoined cat and dog caused this duo quite a bit of challenges. Coupled with the dark humor and sometimes creepy animations, the show could be deemed unsuitable for kids.