Can an ent doctor tell if someone smokes?

Probably yes: Chronic smoking has deleterious effects on the nose and throat. Nasal congestion, nasal drainage, and nasal obstruction may occur. The throat is often red and swollen and finally chronic inflammation of the vocal folds and even cancer of the tongue, tonsil, and larynx may all possibly occur. Sometimes one can pick up a smoker just by the tobacco odor the skin emits. So yes an ENT doc can tell.