I have same prob for years with my wife's car
the white marks is really annoying when we drive during raining time at night.. (the spot mark appear when running the wiper, it occurred at driver side view only)

I never use any WM removal all this while..
but my wife maybe tried some kind like Rain-X b4

past 2 weeks I use Joy Dish Liquid and brush it with Scoth-Brite (non-scratch type), it it does improve..
now still monitoring..

is it windscreen prob ? or it is a tar/stain instead that cannot be removed by normal car shampoo ?