Poor FM reception clean the window ?

This was crazy I was asked to look at a car with poor FM radio reception especially when raining. The antenna was
in the rear hatch heated window, the customer had already swapped the head unit and antenna isolator booster for junk yard parts with no improvement. After checking powers and grounds I did a bit research in one make forums on the web the solution was simple clean the glass inside and out with alcohol.

Fixed? Never heard of that one

That's weird...
I'll give that a try on the old lady's Honda Pilot.

It seems to have worked, the main issue annoying him was it was picking interence from the various motors inside the car, wipers and heater blower that seems cured the other problem was weak signal between towns on longer journeys no feedback on that issue yet.

Wonder if it stayed parked in an environment with a lot of metallic dust.