Never thought of what my sims' houses would smell like, but depending on who's house you visit and the time of year, I think they would most probably smell like coffee or tea, freshly baked cookies or some homemade dish, fresh laundry and likely pet smells. And some houses have fireplaces, so some warm toasty fire smell too. And some that live in wood cabins would probably smell of wood. I have a couple that lives in a dusty old house, I imagine it probably smells like dust and old perfume and cigarette smoke and a sim who lives in one of those TLC apartments with bad drains and bad airflow, so imagine it must smell like drain pipes and probably neighbours' cooking.
