 The garbageman suit of Christoph Sieber (qv) was a new and clean  one so they added some real dust and dirt from the street shortly  before shooting to make it more authentic. They did the same for the  suit of Vince Ebert (qv). Jörg Hofmann (qv), a real garbageman,  used his actual working suit so this procedure was not necessary for  him.