Yes, it is legal in SC. However, I describe the unit rather than the tenant:
"this home has been maintained as nonsmoking"
I ask about smoking on the application form, and have extra fees for smokers on the lease: $200 nonrefundable fee, and additional $25/month rent.
For those that tell me they will only smoke outside, I also have in writing I charge $1 per butt to pick em up out of the yard. I make it clear they would rather rent from someone else if they smoke.
I have had a few smokers, and at least one paid some big money for damages after the fact.
--141.129.x.xx