I don't believe you because that’s what happened to me and I did take all four corners apart and not only were there no water markings but I didn't even see any signs of water.
By encased in metal I meant, they are inside the a and c pillars, they are not between the interior panel and the pillar, they are inside the pillars (the plastic tubes that is).
You are correct, the drains leak where the plastic tubes connect to the "sunroof cassette" because they just disconnect. Gravity would carry the water down the pillars. Actually, I don't even want to try to explain and reason through this because I've had this problem and I know that water collects behind the front seats (when the leak is in the back) and I also know that in that case there are no water markings on the cloth of any interior panels except for the carpet. I've had this leak for over half a year if not a year until I finally got to the bottom of it and even after all that time, there were no water markings (the car is never garaged and I personally wash it religiously).
What I would like to say is, the person who asked for advice heard both sides and there is no reason for us to argue about things like this.