The paint style Yoshi's Island for SNES and n64 had, I think some RPGs had it too, like Moon.
The art style for Ratchet and Clank slaps.
The characters look goofy, but also grimy and edgy, and so does the whimsical environment.
Spore Hero's art style is fucking beautiful.
It's all whimsical, covered in spirals, and bright textures, with weird creature designs.
Psychonauts
The unhinged and disgusting characters, off-balance terrain and structures, dark colors.
Little Inferno
A grim but slick look, almost like Don't Starve.
Little Big Planet
It's uneven, and the semi-photo-realistic art style helps with the materials and textures.
Mario&Luigi
It's wacky, zany, but also slick and paint-like.