Meth mouth from cigarettes?

I have been smoking cigarettes for 5 or 6 years now, at least a pack a day, and i have noticed that my teeth have black spots on them. I have since cut out a pack of cigarettes a day and only smoke maybe 2 cigars a day. I am going to go to the dentist soon but i have found that those black spots are not going away. Is this a sign of bad teeth decay or should i be worried about it getting worse? Does anyone have this problem as well?