Crowley first saw the angel from behind. White robes, wings, hair, and skin.
The usual he supposed, but there was (is) a softness that was (is, always is) missing from the other angels. It gave him pause, and with that pause his attention was snatched by the hair.
So beautiful and curly (almost like a lambs).
He wanted (still wants) to touch it so very, very badly. It looked so soft and silky, flowing in loose ringlets to just touch the angel's wings. The light causes the hair to shine in such a lovely way.
He even flicks out his tongue to, hopefully, catch the scent!
After the humans leave he slithers close to the angel in hopes of the wind blowing the hair close enough to touch.
Just a brush would do!
God- Satan- someone save his sanity!