Ataru+Lum:
She always punishes Ataru with high-voltage zapping.
Many Earth boys want to be punished by Lum, but Lum only wants to punish Ataru.
So boys think that she is attractive because they can get Lum.
SonicxReiHino:
I agree with you all about Lum's attractiveness when it comes to her character but physically i like to think its her hair. I could think of that color and she comes to mind. Its like her hair with its specific color brings out her personality and I like that. She can be mysterious or unique.
Megane:
Fumi Hirano's voice contributes a lot to Lum's character. When I hear her sweetly say "Darling" my kokoro goes dokidoki.