I have been wondering this for a very long time and have not seen it as a thread on this forum since I joined 2 years ago. Keeping in mind that aromatic and English tobacco pipe smokers tend to segregate, which of the two general tobacco categories produces the most stubborn ghost? I tend towards mild aros so an English ghost is more tenacious to get rid of but I keep hearing members complain that the aros are a pain for English smokers. What gives?