(I cannot stand cigarette smell) In any case, my landlord tried getting rid of the odor, which was always temporary and basically smelled like a "pretty smell" mixed with the cigarette smell.

We had all the walls scrubbed with ammonia and citrus but that only took some of the yellow of the walls, not the odor.

The previous owner was a pipe smoker.You shouldn't have to worry about the odor in my experience, there are tons of ways to get rid of anything lingering.

I'd paint the floor with Kilz for good seal, something I've used with pet odor in homes to block off and seal the odor then lay down the carpet/tile/hardwood/ or vinyl plank flooring. next, what are  you trading off by doing this - might be cheapest but is it really?

What's a good way to remove the odor for good?

I tried contacting a couple of deep-cleaning companies and both turned me down for cleaning as they feared potential liability with it being fire damage and the odor remaining.

We do not allow cats period because of the odor damage they can do down to the sub-floor if they spray carpet and padding.

I plan to sell this house after repair, real estate agents tell me that it is impossible to remove the odor.Andy suggestions to remove the odor would be really appreciated. 

Ozone won’t remove the source of the odor.

I still smell the odor, and I hope to start on the walls today.Ofgift