The worlds best primers do a great job at blocking stains but little can defend the odor.

With regular annual inspections including scheduled spraying for prevention of insects/bed bugs as a former employee of a broker and as a tenant my observation shows 10 years is about the maximum.Personally, in my opinion carpet is highly unhygienic, attracts odors and has a short life compared to hard surfaced floors and it amazes me that it has taken so many years for the trend to switch reflected in more apartment complexes featuring hardwood (I'm in Reno, NV where there has been a surge of bed bugs so this may be a big part of the switch-regular preventive fumigation in addition to that for prior to move-ins and outs is common too.)

There's a product that works great for smoke odors.

Just need to get rid of some left over pet odors...

But, if you enjoy the smell of money, ......I'd guess that similar to a house radiating the stench of cat piss a house that perpetually smelled like farts would have the "Smell of money" odor to it.Now this is assume the source of the farts could be identified and eliminated.

That odor is hard to get out of rubber and will eventually rot it away.

I am under contract on a unit and when I went in for the inspection, the current tenant was sitting on the couch smoking cigarettes inside, as if he has been doing it for years.My question is, in trying to determine if I should buy this unit or not, how hard is removing smoke odor from a unit; meaning the carpet, paint. etc.

Odor of smoke in bedroom3.

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?