Sometimes you walk into a room and smell Cardassian. This can cause panic for some people, so be careful where you take guests.
Cardassians don’t sweat quite like completely mammalian species do, but their breath stinks. Whether this is natural or artificial, maybe for intimidation, it’s not known. Their military armor is a noxious amalgam of rubber, false leather, and metal. It’s a distinctive combination; people who lived through the Occupation of Bajor associate it with terrible things.
DS9 was scrubbed clean of Cardassian stench when Bajor claimed it, aside from the tailor shop and quarters where one still lives. However, it seems that the Cardassian smell sunk into the carpets, slunk into cluttered corners of docking bays, insinuated itself into the cracks between light fixtures and ceilings, pervaded the very metal of certain closets and access tunnels. DS9 doesn’t smell like Cardassians anymore, but when certain places are disused for long enough, that smell creeps out of its hiding places.
Smelling that unexpectedly can cause panic or overwhelm for survivors of the Occupation, so be careful where you take people. Disused rooms, enclosed corners, anywhere small with a carpet should be checked before bringing anyone in.