In spite of his OCD, and possibly because of his Synesthesia, Tyson likes seeing people looking messy.
With Tyson’s OCD, and general dislike of ripped clothes on other people, this seems rather odd. However, with Tyson’s OCD, there is such a thing as good dirt.
He can’t explain why, and paint/glitter/dust/et cetera on his own skin would drive Tyson up the wall, but he adores seeing other people that way. He thinks it makes other people look incredibly pretty.
The moment when Tyson realised he loved Kimiko was seeing her covered in sawdust, and he realised that he loved Sebastian when he was covered in dust from patrolling and gun oil coated his hands.