I wanted to say Sonic runs around naked and nobody finds it arousing but I know better.

To be honest, I notice the guys in Sonic usually have a more cartoony body made of a roundish torso with noodle arms while some of the girls have a shapely body so it's not just the clothing (or lack of it) making the girls suddenly attractive.

This all said some kind of clothing will definitely make it more arousing than just going butt naked and acting natural, especially if said naked body has nothing to show.