You can never have enough...

[Oh_hunnihunni]

I use a paste of baking soda, dishwash, with a wee bit of water and one of those plastic scourers on my shower glass. It doesn't get the etched water marks off from the very old glass but it does clear soap scum and shampoo dots off. Cheaper than any of the commercial stuff too, and even with a good scrubbing it doesn't scratch the glass or the plastic. You can use a cut lemon too...