Very happy to report the smell is gone. I didn't do much. I figured I would try an easy approach and if that didn't work, then I would get more aggressive. I wiped down EVERYTHING really well with distilled water and then put one bowl of baking soda towards the top of the humi and a bowl on the bottom shelf. A day and a half later, the smell is gone.

I also found out more from the seller, which makes sense based on the ease at which I got rid of the smoky smell. He explained that the day that he sold me the humi, he had the door open for a couple of hours or so while unloading all of his cigars and getting it ready for me to pick up. While doing that, he was puffing away and smoke definitely got inside since the door was open. Sounds logical... but who cares - smell is gone and now I'm good. Thanks for all of the suggestions, fellas.