Sadly I did not take any pictures of this, but to be honest I didn't think of it at the time, I was more concerned about other things at the time.
Park a brand new white corporate jet, a Falcon 50EX in this case, on the ramp at Beijing, China for three weeks and when you come back, it is brown, from the pollution in the air.
This is what it looked like when I first parked it;
Now imagine all the white color, now the color of mud and you've got it.
I was able to have it cleaned in Singapore a couple of days later.