Over here it rains very often. So if you go out for a drive you have to expect that you will see rain.
It is not really that bad, it's the same chemical formula we use to wash them in
But what can be bad is road grime that comes with the spray from tires and other cars. It is better to get it washed away as soon as possible. The paint is made to handle that but our polished aluminum wheels are more sensitive.
As Steve I am not going to sell my car ever, so the value is not as important, except keeping its proper value insured. But it is of course always nice to keep the car in good shape.
One thing to keep in mind though, with a powerful engine and wide tires rain and wet roads can be really dangerous, aquaplaning can happen easily with our kind of cars.
Jan