I had the exact same problem - house owned previously by heavy smokers. There was a lot of finished (but unpainted) woodwork where I did not want to repaint, but it held the lingering odor of cigarette smoke. After spending who knows how much money on countless specialty cleaners without success, finally I sprayed some Formula 409 on it. It worked VERY well and did not harm the wood, and finally that awful smell is gone! I feel like I have a new house! I recommend it to everyone facing a similar problem.