Weird. I think this bothers some people, and not others. I quit smoking a long time ago, but I was a closet smoker for a fairly long time, and some of my good friends DID NOT KNOW I smoked. I was always careful about only smoking outdoors and standing so the wind blew the smoke away from me.
Later, after I quit (and thus came out of the closet with it), I found out that a lot of people truly didn't know, and never smelled it. Except Lorelei, she could always smell it. I could smoke one cigarette outside with the wind blowing away from me, and then change clothes and Lorelei could STILL smell it 6 hours later. I would hate to be that sensitive to it.