Every long-term smoker I've ever known coughed up green phlegm. My mom did it before she quit smoking. She had smoked for 30 years and sounded like she was ready to expel a lung at any moment. She's been off the things for nearly 10 years and the only time she coughs like that now is if she has a cold. To me, the green stuff is proof positive a smoker is damaging his or her lungs.