The tongue detects only a small set of basic tastes. Nearly everything else — the pepper, the cedar, the cocoa that people describe — is aroma, detected by the olfactory epithelium high in the nasal cavity. Reaching it from inside the mouth is called retronasal olfaction, and it is the same mechanism that makes food taste of nothing when the nose is blocked.
How it is done
Smoke is drawn into the mouth and then exhaled gently through the nose. It is not inhaling: the smoke never goes to the lungs, and the two are routinely confused by people describing the technique.
Why it can be unpleasant at first
The nasal passages are far more sensitive to ammonia, pepper and capsaicin-like compounds than the mouth is, so a full mouthful pushed through the nose can be genuinely harsh. A small amount, gently, is the usual advice.
What it reveals
It is the difference between describing a cigar as strong and describing what it is actually like. Most detailed tasting vocabulary in any category comes from retronasal aroma rather than from the tongue.