Golfs have a common problem of the water running down the windows in the doors, (cant be helped, its natural) the water then runs off the window down the inside of the door, take your door card off and you will see a large metal plate holding the window motor in and a few wires. The rain water eventually rots the the metal plates seel away and the water then gets down through the bottom of the door card and into the car
if its in the rear it wont be pollen fillter.Have you got a sun roof.