>>5140329_(OP)There is ABSOLUTELY such a thing as objectively bad Character Design!!! The fuck kind of pleb question is this. Design and art are two different things. Something that just looks kind of cool without any purpose or use of semiotics is bad design, characters are no exception. Good character design involves using regoznizable indicators relating to the character's personality or trait (ex: Walter White's cancerpatient head, Prince Zuko's Eye Scar from Avatar, etc.) It also involves making it (usually) simpler so it's easier to draw/load in a game/inexpensive for a costume. The subtler the better imo but there are exceptions that I can't think of.
When it comes to japanese anime, the holy trinity for character design is Naruto, Dragon Ball Z and Jojo. That might seem like a normie answer, but ask yourself why the normies like that show so much. What is it that makes a show like Naruto so appealing despite its constantly shit story. Simple answer: amazing character design.While bad character design alone usually doesn't break a product, it certainly makes the characters super forgettable. And good character design almost always saves it.
Ignore every single one of these uneducated responses OP. Watch yuper eyepatch wolf's video on Character Design on YouTube.