I don't think that is a valid reason to refuse adoption. However, I don't think kids/pets/other members of the household should have to be subjected to cigarette smoke. My personal opinion is that if you want to smoke, thats fine, but smoke outside/away from other people/pets. Many of the people I've worked with smoke, and I don't care one bit, as long as they do it outside, the smell of cigarette smoke makes me ill, literally...honestly I wouldn't want my dogs to have to breathe it in either. I would not refuse to adopt out a dog if the people smoked though.