The conventions of the post-apocalyptic cinema enforce a specific aesthetics, and its visual dominant is often dirt. This element is usually contrasted with the alleged purity of the world before a catastrophe. Mad Max: Fury Road (dir. George Miller, 2015) seems to be an example of this strategy. However, the article shows that Miller’s work reveals an interesting ambivalence: suggesting the legitimacy of the dirt-purity opposition typical of the convention, the film simultaneously undermines it. Therefore, in Mad Max: Fury Road we can see three different systems of meaning based on these categories. The first one is a consequence of the accepted convention, the next two show the original author’s vision and represent a successful artistic attempt to overcome the typical perception of some features of the post-apocalyptic world. The article uses elements of Roland Barthes’s semiotic analysis of film, as well as Mary Douglas’s findings on the category of dirt and purity in culture.