No, its the smoke that you didnt get while taking a hit, thats why there's usually a pull-carb. Pull the card and hit the rest of it, the reason you might cough is because of the oxygen that is being pulled in along with the smoke.
Demon420 Reviewed by Demon420 on . Stale smoke...? ok, so u know wen u take a hit from the bong, and sometimes theres that "devil smoke" or "ghost" left in the bong, which is basicaly stale smoke that if u inhale, it tastes so bad, and makes u cough? can some1 explain the science behind this? Rating: 5