We bought a house last year and the place smelled just awful when we first bought it.
We tried just about everything to get rid of the lingering odors, but they were still there and they got worse every single time that the heating or cooling system would kick on. It was really bad at the beginning of the summer when the temperatures outside were really heating up because the minute that we first turned the central air conditioning unit on, the house became almost uninhabitable because of the terrible odor. I wasn’t even sure what the smell was at first because it was so randomly disgusting. It wasn’t like a normal bad smell like a skunk or like old cigarette smoke. It was something sweeter and just sickening. It turned out that they had used the house as a perfume storage facility and I guess at some point, a whole case had spilled and soaked into the wood floors. We didn’t want to replace the gorgeous wood floors in the house, but it was really hard to try and live in this place with the awful odors. Literally every time the air conditioning came on during those first few months in the house, my eyes would start watering from the smell. We finally replaced a portion of the flooring and we had our HVAC company come and install a whole home air purification system in the house. Now at least we feel like we can breathe again. The air purification system has definitely helped with the indoor air quality.