A stuffed animal that an adult might find unpleasant due to its smell could be a cherished toy for a child, showing how personal experiences with scent can differ greatly. Similarly, the smell of Camembert cheese may stimulate appetite, while the scent of spoiled food often causes discomfort. These examples are part of a public workshop titled Why does it stink?, organized as part of the Science Festival 2026. The event examines the smells of waste as clues to our lifestyles, consumption habits, and how we remember things. The workshop takes place at the Village of Sciences at the royal abbey of l'Épau in Le Mans, Sarthe, on October 10 and 11, 2026. It invites participants to think about how scents can bring back memories and evoke emotions, with the stuffed animal being a clear example of how one object can mean different things to different people. The workshop is based on the concept of "Rudology," a systematic study of waste started in the 1970s by geographer Jean Gouhier and continued today by geographer Mathieu Durand and his team at the Espaces et Sociétés laboratory in Le Mans. This approach looks at waste not only as a technical or cleanliness issue but also as a social and geographical phenomenon that reveals our daily habits and ways of life. Smell plays an important role in making these questions more concrete, as it can cross the boundaries we set between spaces, drawing attention to issues we might otherwise overlook. It can also make us think about what changes, what transforms, and what stays the same. Describing a smell is complicated, as it involves more than just calling it "good" or "bad." It can be wet, sour, earthy, or sweet, and may remind people of specific places, foods, or memories. The workshop includes an olfactory recognition test, allowing participants to explore and compare their impressions of smells related to food and textile waste. The goal is not to define smells but to show that trying to find words for them helps separate the physical sensation from the emotion it causes and the judgment we make about it. The workshop encourages people to think about why certain smells are considered unpleasant and whether objects meant to be thrown away necessarily lose all value. The event is free and open to the public from the age of seven, and it is designed as a street activity within the framework of the Village of Sciences in Le Mans. It is labeled as the "Heart of 2026 of the Science Festival," which takes place from October 2 to 12, 2026, with the theme Scientific Flavors.