Why would cigar smoke make it unstable?To me it seems to be going against what we try to accomplish with a humidor. We are trying to create a perfect state where cigars can be stored and aged properly. Then you add cigar smoke to the picture and it becomes unstable imho. I wouldn't want it to hurt the cigars in any way so I would never do it myself.
You realize that many of the workers smoke WHILE making cigars, right? They smoke as they walk through the barns with the tobacco bales and probably while they stack and restack bales, they smoke while harvesting I'm sure. These things are around smoke throughout their construction.
They really aren't that freaking sensitive. If they were then we'd see more airlocks on humidors...
I wouldn't go in there and smoke an entire cigar, but you aren't going to hurt anything if you smoke while you pick out your next cigar. People smoke in the humidor all the time at the shop I go to and there is never a problem with smells and it never affects the cigars.