People who post on another forum, for an autoimmune condition called Sjogren's Syndrome, also have this symptom.

I usually smell smoke, several times a day. In relation to nothing in particular as far as I can tell.

Also my sense of taste and smell is somewhat impaired at this point. Probably by my dryness syndrome.

It takes a while to get used to. Fortunately I don't have the dirty socks odor appearing.

Hugs, Elaine