Her first emotion was fury at herself.

She must be losing her mind not to have suspected! Then the fury overflowed on Worth and his companion.

It reached high-water mark with the stranger's smile.
And there dissolved; or rather, flowed into a savage interest, for the smile enticed her to mark what manner of man he was.

And as she looked, the interest shed the savagery.
His sleeves were rolled up; he had no hat, no coat.

He had been working with something muddy.