[PeteSB75]

It depends on how often and how much the room has been smoked in, as well as what type of flooring/furniture is there. Hardwood floors and leather furniture hold a LOT less smell than carpet and fabric. If you have the former, just putting in good ventilation or a very good air purifier should be enough. If you have fabric/carpet, there's not much you can do. You will get some residual smell, though less if you ventilate well. Shampooing the carpets/furniture will help somewhat, but not completely.