My car when it's not clean looks like the picture. I thought it was due to the rainy days. But it has been like that for a long time. I had to take out the door panel (because of the window regulator that broke) and I saw that all the dust and dirt inside was totally wet! I touch the outside part of the door and feels wet too. And it is not only at the doors, all the car!
I don't know what to do, it can oxydize?
With a vacum cleaner is impossible to reach all the places, it's like mud, not dust inside.

 

Nobody knows?