I say fold if the smoker looks natural and relaxed. call if the smoker is looking a bit jittery or mechanical. I use to be an avid chain smoker even more so at the poker table. I noticed that whenever I was dealt a good hand or caught something I would immediately grab a smoke and light up. Mike Caro's poker tells states that if a smoker is blowing the smoke in your direction and is very talkative while smoking and relaxed then the player probably has a monster and you should fold. Just the opposite if the smoker is stone cold and does not respond and just smokes then they are probably bluffing.