The line to draw seems pretty clear. If you're renting out a portion of your primary residence (or a subunit of your primary residence like a basement apartment

The line to draw seems pretty clear. If you're renting out a portion of your primary residence (or a subunit of your primary residence like a basement apartment or guest house) then that's fine. If there is no permanent resident in the dwelling and it's being managed by a 3rd party, it's a hotel and should be subject to all the regulations other hotels are. Building codes already have a delineation for these different types of properties.