If you go to a real Train site, like a yard or Industry switching, there are certain smells that are part of the experience which are not on a Model RR. Creosote is one of them, also oil and diesel fuel.
Sounds too…The Rumble and Whine of the Diesels …that cannot really be duplicated even with the best DCC sound through a 2 inch speaker on a Model RR, but instead sounds like a telephone.
A model steam Loco I had, was equipped with the Smoke unit and that added some realism
as the smoke oil must have had a petroleum base according to the smell. Better than nothing.
Obviously, health is a factor.
I remember many decades ago there was talk of inventing “Smellivision” to give off certain odors
that match whatever TV show was on. I guess no one ever figured out how to do that.
I got 2nd degree chemical burns from unloading a semi trailer full of new creosoted cross ties in the summer of 1979. We got to the job site before our tools did, and our foreman insisted that we unload the ties by hand. Four 18 year olds, 400 miles from home, did not have the common sense to say no. My gloves soaked through. It was a tough week.
Twenty or thirty years ago there was a company marketing scents for model railroads; I am pretty sure one of them was cattle manure (or as we say in Dodge City, home of two LARGE packing plants, the smell of MONEY!).