Yes, i believe that smell has a psychological association, and can be re-experienced, even in the absence of the source of the smell. Two experiences in my life have convinced me of this. The first was my proximity to a an explosion in Belfast in the early seventies. The noise was terrifying, but the worst was the smell associated with the aftermath of the explosion. I will not describe the smell, as it might be distressing to others reading this post, but it was this that returned to haunt me in succeeding years. Secondly, As a student needing to pay tuition fees, I worked night shifts in a nursing home, where an elderly man suffering from diabetes developed ulcers in his legs and severe gangrene in both feet. I was very fond of this old man, and although the smell of his illness was unbearable at times, I spent a lot of time with him. Inevitably he died, but over a period of about two years, the smell would return to me unexpectedly. I always felt an immense sadness when this happened and grieved for the old man all over again. No 0ne in my family could notice the smell and I believe that it was part of my own individual grieving process, brought on by profound emotional experience. Your experience with the nauseating smell in the dustbin may be part of a similar psychological process, in which a smell which has had a profound effect on your emotion (in your case, profound horror) can be re-experienced and can provoke the same emotional response that was associated with the original experience. In short, I believe that our sense of smell is involved in the experience of Post Traumatic Stress, and it is this that haunts us after the event. Your re-experiencing of the smell will fade, distressing though it may be. The reassurance from others that they cannot smell it will give you confidence that your experience of the smell is merely a memory.