I started dipping four years ago to quit smoking. I don't hear any shit about second hand spit, so I'm pretty happy.
I will give you a ration of shit. Seeing anyone spit makes me physically ill to the point of having to fight to keep from throwing up.
True story = I had to give a presentation last year to some of our field guys, as in, guys from OK and west TX who turn wrenches for a living with greasy fingernails. I walked to the front of the room of about 40 people and faced them to begin speaking, only realized that all but about 8 of them had a spit cup in front of them, including the one female mechanic.
They say you are supposed to make eye contact with your audience as you speak, but that was not going to happen in this world or any other. I gagged once when I realized what was going on (hell, I gagged just now thinking about it...), and thought "There is no fucking way I can get through this speech without literally puking on that guy's steel toed boots..." But then I saw a fire sprinkler on the ceiling near where it met the back wall, and gave that fire sprinkler the best training in the world about our warranty obligations to our customers.
So yeah - second hand spit is nasty, unhygenic and makes me want to puke.