I think John hit the nail on the head for your situation.
Per
AB&B website, taxes are paid on AB&B rentals in SC. As a normal rental agreement does not collect taxes, the Board can utilize that argument (those activities where sales and other taxes are paid, or should be paid) as adefinition of commercial business.
The link is provided above (which covers all States).
However, this is what it posted about SC:
State of South Carolina
Guests who book Airbnb listings that are located in the State of South Carolina will pay the following taxes administered by the State as part of their reservation:
South Carolina State Sales and Use Tax: 5% of the listing price including any cleaning fee and guest fee for reservations 89 nights and shorter. For detailed information, visit the South Carolina Department of Revenue website.
South Carolina State Accommodations Tax: 2% of the listing price including any cleaning fee and guest fee for reservations 89 nights and shorter. For detailed information, visit the South Carolina Department of Revenue website.
Local Taxes collected by the State: 0.5-8%, per Local Tax type, of the listing price including any cleaning fee and guest fee for reservations 89 nights and shorter. One or more of the following Local Taxes may apply: Capital Project Tax, Catawba Tribal Tax, School District Tax, Education Capital Improvement Tax, Transportation Tax, Local Option Tax, Tourism Development Tax. Note that Airbnb is only collecting the Local Taxes that are administered or collected by the State at this time. For detailed information, visit the South Carolina Department of Revenue website and the Sales and Use Tax Manual.