I can remember when every Wednesday night my husband and a few of his buddies would have their poker night down in the basement. Halfway through the night I could notice the cherry or vanilla smells coming up through the heat ducts from all the cigars they were smoking downstairs. I would always open the window and put a fan in it to vent it out. Its a wonder that they could see with that much smoke. On the other hand the basement for days after that would always smell sweet.