My question is this: which of the two will wash his face?

I am currently reading The Zahir by Paulo Coelho and came across something in the book that really had me thinking.

I'm going to ask you the same question that the book asked and not tell you the answer immediately. I am curious as to how you think!
I put this out to some of my friends and received some rather creative replies. XD

Quote-

“Marie, let’s suppose that two firemen go into a forest to put out a small fire. Afterwards, when they emerge and go over to a stream, the face of one is all smeared with black, while the other man’s face is completely clean. My question is this: which of the two will wash his face?

What do you think is the answer? Who do you think will wash his face? 

Once you have commented with your answer, you can see Coelho's reply in the book here-

Marie :That’s a silly question. The one with the dirty face of course.’

Coelho:No, the one with the dirty face will look at the other man and assume that he looks like him. And, vice versa, the man with the clean face will see his colleague covered in grime and say to himself: I must be dirty too. I’d better have a wash.’