The glass shower screen may not ever look clean due to "glass cancer" where minute bubbles eat away at the glass. Shannon Lush has an answer to this. I think it is Goanna Oil rubbed into the glass which fills the minute holes and lasts for a few months, before needing re-coating.
I am not sure it is Goanna Oil but you could google Shannon Lush and check.
Think it's sweet almond oil, Wylie.
Travelling at the moment, and can't check.
cheers