You should also mention that defective and/or improperly installed AAV’s are a common cause. . .
When I go into a Home these days, the first thing I do is go through the house and flush all the toilets and run water down all of the drains, so as to minimize any risk of sewer gas exposure to me. I also let the bathroom fans run for a while.
I would mention to Empty Nesters Nick, to periodically run some water in Bathrooms formerly used by children that no longer live at home.
I have had more than one Client or Homeowner tell me about one bathroom in the house that always smells, and it is most often the unused bathroom with dried out traps/toilets
No mention of the most common cross connect between the sewer system and the indoor air would be the condensate drain on the A/C system