After returning from Florida, you can imagine the volume of "bug-splatter" on the windshield. It was well backed on and when I tried to clean it with soap and water it appeared clean until it sired.

SO:
I sprayed the windshield with water, dunked my long-handle brush into soapy water, let it drain and covered the brush with baking soda. I washed
half the window and let it dry to compare.
Results....a pristine window.