What kind of spots? The only thing that I ever get are water spots if I don't dry them quickly enough. I just use some quick detailing spray (any kind will work) and a microfiber cloth (cotton is fine as well). I also wipe the brake dust off daily with a cloth (dry) and they stay perfect.
My old chrome rims always got dirty. One think that I found that helped was to apply Zaino. SOunds silly but it worked! Helped keep the brake dust off a little longer.
Soap and water always did the trick for me when cleaning them. Hope this helps.
To maintain your chromies you should buy a another set of rims. This winter is projected to be very bad., and you know how the north love to use salt on the roads. This time it will worse. Other than that , you should use Mothers. If you know someone on the inside, You maybe can score on som NavalJelly which is supposed to be the best chrome replinisher out of all the other chrome protectant products.