In the spring of 1946, Jean Dubuffet presented the series Mirobolus, Macadam et Cie/Hautes Pâtes at the Gallery René Drouin. This exhibition has rightly been cast as a breakthrough event in the cultural landscape of the immediate post-war period; it was the first public unveiling of Dubuffet’s matter painting and the press erupted with cries of ‘cacaïsme’ and ‘peinture à la merde’, pronouncing him a ‘peintre en excréments’. The critical reception of this exhibition is part of the historical record. This article examines the popular (and even less sanitised) reception of Dubuffet’s contentious hautes pâtes, as recorded in several completely overlooked documents from the period, most notably the exhibition’s ‘livre d’or’ or Guest Book. Littered with swastikas and the francile, the insignia of Pétain’s collaborationist regime, the anonymous comments inscribed in the pages of the Guest Book charge Dubuffet with ‘décadence totale’, characterising his art as ‘judéo-décadent’. Despite the fact that the series avoids any reference to contemporary events, the materiality of his work raised anxious references to the polemic on decadence waged during the Occupation as well as to the post-war political purges of Nazi collaborators.