I have been smelling strong cigarette smoke for the past few years, since my Mum died. I assumed it was her since she was a smoker but it was much stronger than her smokes, I was smelling something closer to a cigar or pipe. I figured that since I have almost no sense of smell, maybe she had to beef up the smell for me.
I asked a psychic who it was and she said my Grandfather who had been with me my entire life. I've never met my grandparents so I had to check the dates to see which one it could be. As a test, I asked a second person who was making the cigarette smoke and he also said my Grandfather. I still need to confirm whether he was a smoker or not but I am following up on that.
Spirits will use smells to get our attention since we often associate memories with smells. I also think we are less likely to ignore a smell and there's less sensory interference with smells when compared to sound and sight.