yeah whatever!!!!
MY EXPLANATION...........
I actually find it easier to add more vinegar to my fairy in summer, which gives that added sparkle, being acid seems to break down the fly deposits, spider web ends etc. etc.
Also using pure water seems just to clean it better
Been using wfp since end of feb and been toying around with things as you do
Many of my customers ask why my windows sparkle more than their OLD w/c
Maybe thats why