In the context of sharing services, this research examines how ambient scent can improve the perception of the presence of other sharers. Four experiments conducted in real conditions (open-plan workspaces, car-sharing services, rail-stations, and library) show that the diffusion of a clean scent promotes positive attitudes toward sharing space with others. Three alternative explanations are assessed: 1) perceived cleanliness of the space; 2) other users' behaviors; and 3) user's mood. The results indicate that throughout the four experiments, the effect of scents is mediated only by the positive mood induced by the scent.