What climate are you in?
Keep in mind that the slab is cool and near the dew point of the outside air most of the spring/summer/fall in most green grass climates. It is critical that you maintain <50%RH through these seasons. Also most home do not get enough fresh air change during the mild season to purge the indoor pollutants. The odor problem is not going to controlled by fresh air ventilation but by finding the damp spots in the home.
Consider a whole house ventilating dehumidifier for the "<50%RH" part and fresh air. If that does not fix the problem, crawl on your hands and knees searching everycorner for the damp spot. Long term <50%RH usually fixes most. I work with Ultra-Aire and we fix these problems routinely. Follows with specific questions. Several on the forum have had the experience.
Regards TB
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"