One of the reasons that non-smokers tend to exclude smokers from their social circles is the fact that they feel that their friends directly harm them as a result of second-hand smoking. Many smokers are confident in their abilities to quit whenever they want to and actually emphasize this concept when they are faced with the dangers associated with smoking. Smokers also tend to marginalize non-smokers because smoking is an addictive activity and because they associate it with social circles where most people smoke. Smokers are probable to associate cigarettes with a lot of activities that they perform on a daily basis, thus meaning that they tend to associate times when they are not smoking with things they do not enjoy. While it is easy for some to refrain from taking on such attitudes, others are likely to feel uncomfortable knowing that particular groups put across unappreciative attitudes concerning...

One is likely to distinguish between a smoker and a non-smoker as a result of each person's behavior and as a result of a series of concepts associated with a smoker. A smoker's smell, appearance, and thinking are all traits that can indicate his or her habits.
All things considered, even with the fact that many smokers cannot be differentiated from non-smokers, it is likely that a particular act that they perform as they interact with individuals is going to indicate that they are smokers

Works cited:

Anderson, Judith, "Smoking," (Black Rabbit Books, 30.07.2005)

Viscusi, W. Kip, "Smoking: Making the Risky Decision," (Oxford University Press, 1992)