What does mold/mildew smell like?? I am renting a duplex that has a smell I can only describe as urine. It seams like it is getting worse over the past 3 months since I have been here. I do not have any pets. I do not have any carpet. I have not seen any pets when the new people moved in next door. (last week) and there were non before. There are plenty of squirrels outside as I live next to a large bunch of trees, and ditch.