I tend to wax/buff my windows a couple of times a year. My 07 ES350 Ultra Luxury has sat outside for most of its life being that I am at college and what not. I am pleased to say that there is not a single spot of acid rain damage or water spots on my car, I have taken impeccable care of it, it just depends on how much effort you put into it

The water ALWAYS beads up on the glass the water just slides off better than any car I've driven!