Its realization should possess aesthetic and artistic validity. Nothing grotesque or distorted or ugly is implicit in the standard. Because they violate in some way the basic concept. In a poor or amateurish work of art, some parts clash or can not be harmonized with other parts. There can be much brilliance coupled with abysmal weakness.
Artistic unity is impaired or absent.
In other words, something clashes with the style. Excessive exaggeration, distortion, or contradictory parts create a grotesque instead of a pleasing image. Intentionally distorted and exaggerated features can create also a ludicrous or comic effect. Such is the nature of caricature or cartooning. However, the ideal standard does not imply intentional distortion of any one part at the expense of another.