Q. Why is it, curly hair never looks quite as shiny as straight hair does?
A. Curly hair never appears to be as shiny as straight because when the light hits the waves/curls, the light is diffused from hitting all the different angles of the hair. In straight hair the light hits the hair and reflects the light evenly making the hair appear shinier.
The same can be said for hair that has been damaged or porous, when the hair is damaged, the cuticles lay open and not flat, therefore the light is again diffused with the angles of the cuticles, hair in good condition has flat cuticles so when the light hits, it reflects the light evenly.