Being a former smoker, I use to spit all the time. Still do when I brush my teeth, but I am so glad I don't have to spit so much anymore.
I have to say though, when I did spit, I did not ever want others to see me so I always did it while alone if at all possible.

I do have to spit quite a bit while bike riding though because it does seem like my mucus membranes go into overload while exercising. LOL
I still wait and make sure there is no car or nothing going by, and on an organized ride, I make sure no one is around if possible. It's gross to me to see someone else do it, therefore I should prevent myself from doing it in front of others if I can.

My son doesn't spit, of course he is only 13 so I guess I shouldn't speak to soon.