Yes, sometimes I smell things that can't be there. I've smelled flowers/perfume before in my boyfriend's house that was the smell his Gran wore, and other smells in various places, like the smell of people I know.
Reading this thread has made Azrael all playful! I can smell the stone of my favourite cathedral and I just asked him for the smell of our garden in the summer - now I can smell the fresh, warm air, pollen and grass - and the washing on the line!