I guess I misunderstood the comment someone made about RaineX. From this statement I interpreted an expectation that Rainex would not remove the water spots and residue:
"Rain did not wash the residue off my windows. Nothing would remove it until I got the (mildly) abrasive product I mentioned above. Possibly my windows are etched by salt, possibly I didn't get them really clean (I did the normal window cleaning with Windex or something similar)."
Yes you did misunderstand it. It was a reply to someone who posted that the excess Rain X that was not buffed off would come off when it rained.
If you read the entire thread from beginning to end you will understand it and understand that some folks have had good results with the product and some (including me) have not.