Don't get into bidding wars. Let someone else pay too much. I have been astounded at the condition of some of the items I have received. It might look like a mint condition book on the outside, but it can stink to high heaven on the inside. Only Titan Games sent some things bagged and boarded.
Smoke comes from being used in games, and mold and mildew from being locked in a closet for years.
I have received one game that I've had airing for two weeks because it smells so strongly of mothballs. Typically when we ask about stuff we wonder what it looks like, but after twenty plus years that old Traveller stuff can have some powerful funk in it. These are just a few observations from a Screaming Jackass. Out Of Print stuff can be wonderful. Be patient, and eventually you will find what you are looking for.