However, yesterday we returned from a weekend at my parents' vacation house across Puget Sound, a 1960s kit house (cabin, even) coated inside and out with smoke, sand, marine air, fir needles, dog hair, and probably 324 kinds of mildew or mold. (Really, it's charming, and the location is possibly my favorite on Earth, but such is the state of the interior air quality there.) When we came home after that, my nose found with pleasant surprise that our house smelled crisp and clean and fresh.
The difference is possibly due in part to the length of time our house was unoccupied--ten days in the first case, only a day and a half in the second. Being unlived-in and having the thermostat turned down and the windows shut probably contributes to a disused smell of its own. But I can't help thinking the main part of the difference lies in the air we got acclimated to in each case while we were away--arid and new on the one hand, damp and quaintly crumbling on the other. I guess our house's smell lies somewhere in between, and it's likely that whoever enters it will smell mainly the difference between our house and what they personally are used to.
This just goes to show that those designing perfumes, or studying olfactory science, have a heck of a lot of subjectivity to factor into their calculations. I wish them the best of luck.