I left it in a tube by itself, and about 2 years later, the smell was gone. It may have been that the guy was a heavy smoker (cigarettes) and the poster was somewhere near where he smoked, and it absorbed that raunchy, stale tobacco smoke smell, but when it was removed from that environment and put in a cardboard tube, the smell was replaced with the smell of the cardboard tube. It was a Star Wars Empire Strikes Back GWTW 30x40, and I sold it.
Interesting comments in this thread. From Rich's outhouse story to Schan's blood stained B1, and all the gifs. I reckon these are just a few of the out of the ordinary situations that ensure job security for restorers.