Usually that's key for me when no one else can smell what I smell. The last olfactory hallucination I had was when I smelled dog urine in the house for days on end. Mind you, my housemate owns four dogs, but they are definitely housebroken. So I finally asked him if he smelled urine and even asked him to get down on the floor to smell the carpeted runner. His reply was he didn't smell anything. That's when I realized it was a hallucination as I've known myself to have other sensory hallucinations. Not long after my pdoc found out I took myself off my antipsychotic a year and a half earlier that he put me back on it.