To keep your door valves from being damaged, wipe the door from front to back when drying with a cloth.
The other day I noticed a small rubber flap fall to the pavement while I was dying the door after a wash. I was wiping back to front when this happened and I must have snagged it, pulling it out.
Peering under the door, there are two rectangular rubber valves, one toward the front and the other toward the rear of the door. The piece I knocked off was a flapper "door" for one of these seals as they are called. I pushed it back in place, then went around all 4 doors finding that each door was missing one of the two flaps, some the front, some the back.
These flaps apparently act as one-way water weep holes (when they are not missing). Perhaps they place a subtle role in acoustics are airflow as well? The pictures show these valves with the flap and sans flap. The molded arrow points to the front of the car. I ordered 4 replacement seals which arrived a few days later.
So kids, wipe from the front to the rear (along the bottom edge of your doors),