The Dutch and Flemish obsession with cleanliness in the seventeenth century is a well-known cliché, both in modern research and for people travelling in Flanders and in the Netherlands at the time. As a result, cleanliness is often brushed aside in Dutch and Flemish studies and seen as a platitude or a triviality. However, concerns for cleanliness at the time were at the core of an important cultural construction, so much so that the dichotomy between cleanliness and dirtiness seems to have shaped a significant part of Dutch and Flemish literature and visual culture. More than that, the words 'cleanliness' and 'dirtiness' were also used at the time in art criticism and writings on painting. Focusing mostly on daily-life scenes, which can be seen as a link between real life, pictorial representation and artistic practices, this work tackles the importance of cleanliness and dirtiness in seventeenth-century Dutch and Flemish painting, at each stage of the making of a picture and in the way painters think about their own practice. This study follows a cross-disciplinary method, combining art history, cultural and material history, as well as social history, and aims, inter alia, at understanding how these pictures, born from Dutch and Flemish culture, interrogate this culture in return. A broader perspective was also adopted with significant research into art theory, by confronting Dutch and Flemish texts between themselves, but also with European art theory.