I believe that everyone who has ever worked in this industry has experienced a similar situation. Here are some things that you may want to try:
Repaint the walls. Again.
Stale cigarette smoke can absorb into the walls. Serious odors may require more than one coat of paint.
Shampoo the carpets. Again.
Ask a professional carpet cleaner to use heavy deodorizers.
Change the furnace air filter.
It may seem insignificant, but you'd be surprised what a big difference this makes!
Run an Ionizer.
An industrial ionizer fan is my go-to smell eliminator.
When it comes to deodorizers, bring out the big guns.
My favorite brand or deodorizer is
OdoBan
. It disinfects, deodorizes, and leaves a fresh scent behind.
Open the Windows.
Let in some fresh air and sunshine.
And now for some, uh, "creative" hacks:
Canned Air
The stuff you use to clean your keyboards? Yeah. Spray the crap out of each and every outlet with that. It sounds weird, but stale cigarette smoke can accumulate in the outlets. Try it out sometime!
Houseplants
It doesn't take a rocket scientist to figure out that plants make the air cleaner. Or maybe it does. NASA released a list of common houseplants that remove volatile air compounds. You can check out the list
here
. Cigarette smoke contains benzene, formaldehyde, toluene, and ammonia so go plant shopping accordingly.
Vinegar and Citrus Peels
Boil a large stock pot full of vinegar and citrus peels. You will never win a cooking contest with this recipe, but it removes airborne odors.
Believe me, there is hope for your vacant home! The worst I saw was when our formerly white walls were so caked in nicotine tar that they become post-it note yellow. It takes a little bit of elbow grease and a bit of a stubborn attitude, but this is a treatable thing.