It's possible that your sense of smell is sensitive enough to pick up scents and nuances that others cannot pick up. My hearing is like that and sometimes my smell for certain scents is like that also. So it would be difficult to tell if it was a hallucination or not. If your sense of smell is just that sensitive then it is most likely an Autism thing. But I don't know how you could know for sure if you were hallucinating. You might have to be clinically tested to find out.
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"I'm bad and that's good. I'll never be good and that's not bad. There's no one I'd rather be than me."
Wreck It Ralph