but don't worry, it's safely locked down.2) Smell-- figure out the cause, is it a horrible smoker,  bad carpet, or mold? 

Add on potential electrical main panel upgrades to handle the increased load (assuming no gas service, they'll be cooking and heating with electricity in the ADU), along with drawing and permit fees and you're maybe another $5k. 

Every current owner cooks their books- properties are never performing like their proforma says they do.

Cook plenty and don't be so picky with your leftovers where you are free to microwave them for a quick on the go bite on the way to wherever you are going to get out of the house. 

One example for sure was that there were no exhausts over either of the stoves in the units and that was a big thing for me because I cook food on a daily basis.

"Ratatouille" said it best; yes anyone "can" cook, but only few will be great at it.     

I am about to start an Air BnB and am concerned about smokers, pets and general odor elimination between guests.

Cook he's an expert in this space and has sold 15+ Massanutten STR's just like you are describing. 

Plus the ability to cook your own meals, outdoor space, being in unique neighborhoods, etc etc . . ... 

@Ethan Cooke most of us hosts on this forum agree that airdna is a waste of time and we prefer to do our own annayslis.