Dust ???

Dust ??? We have a regular meeting every Fridays. Today too! It started in our meeting room at 9:30 am. After he of another department talked about a new system, he looked at his cloths. Then he said ,"What is it? My shirt is dirty because there are some dusts on my shirt". Everybody who were in a meeting room ,include me looked at his shirt. Then I noticed white dust of his shirt because I was aside of him. It was true that there were a lot of white dusts on his shirt. Then he understood. It were not dusts!! It were powders of laundry soap! When I listened to his words, I couldn't stop laughing. Why were there powders of laundry soap on his shirt despite washing his shirt? I know he married and he has a son. So I tought - His wife might only put his shirts into a washing machine. - His wife might not turn on a button of starting a washing machine after putting his shirt into there. - His wife might think doing washing something was only putting powders of laundry soap on. I hope that she didn't turn on a button of starting a washing machine because she forgot it.