If you ever wonder to the smoking lounges in IAD C and D gates, their ceiling are both yellowish, or I should say almost brown, they have poor ventilation inside with weak fan to exhaust the smoke, but who really care about that ? A smoking room airside is really hard to find in US airports these days. I still miss the smoking lounge inside ORD RCC at C16. I remember I would join the RCC just because of that smoking lounge which closed several years ago.