Physical beauty is relative to species and cultural norms. In most cases it plays no significant factor – unless a character is shallow enough to be swayed by looks alone over other character aspects.
Ugly
The character is ugly.
Average
The character is average. It is not nondescript per se, but that they possess little in the way of striking features. They may have striking eyes, or a chiseled chin, or thick, lush head of hair – but together their is not enough to separate them from the great variety of average creatures of their species and culture. Cosmetics can be used to make the character seem ugly, or striking.
Striking
the character is striking and memorable. This is not necessarily a good thing if they desire anonymity. Blending into a crowd becomes more difficult. Cosmetics can be used to mask striking looks.