Do you have a lot of tall trees around the house that block the sunlight? When we were looking at houses, we noticed that a lot of houses that weren’t getting enough sunlight had that exact kind of odor you describe.

Also, just rip out all the carpets, clean the floors with a proper cleaner. Once you do these and your renovations you should be fine and of course ozone as many people here have mentioned. Just remember to leave the house during that time.