Its my understanding that phantosmia, feeling presences, deja vu, and jamais vu are all potentially signs of problems with one's temporal lobes, sometimes even being indicators of temporal lobe epilepsy.

I think the above are common with bipolar and schizoaffective though based on my conversations with many people. My most common phantosmias have been a smell that is similar to peroxide poured on a wound and something that I have to describe as smelling like burnt metal.