Chances are, Yuusei had run into Carly while she was still testing out her Seeing Stone™, though her glances of him were likely brief; and she's certainly seen him throughout their visit to the Summerlands. She's seen his current state of wardrobe disaster in some form or another.

Tentatively, though, Yuusei still approaches her with his arms lightly hugging his sides. Now she can see him properly, and she can see everything that he thought was a good idea to wear.

He bites his lip.

"...how bad is it." In your professional eyes, of course. Professional eye-rock.