It must have something to do with the sunglasses.
When Nada later dons the glasses for the first time, the world appears in shades of grey, with significant differences. He notices that a billboard now simply displays the word "Obey"; without them it advertises that Control Data Corporation is "creating a transparent computing environment." Another billboard (normally displaying "Come to the Caribbean" written above an attractive woman lying on a beach) now displays the text "Marry and Reproduce." He also sees that paper money bears the words "This is your God." All printed matter around him contains subliminal advertising.They Live
Additionally, he soon discovers that many people are actually aliens, who are human-looking except for skull-like faces. The aliens tend to be wealthy upper class members of society, as well as politicians. When the aliens realize he can see them for what they truly are, the police suddenly arrive.