I've never stayed at South of the Border, but I do enjoy its kitsch. I haven't even eaten a real meal there, just something fast.
I did, however, wind up with a lousy Super 8 motel room a few miles north of there at the Lumberton, NC exit. I'll never know why I thought I should save a few bucks by choosing that instead of the Holiday Inn across the road -- which I'd already been at a few years prior, and it was perfectly nice. Bottom line, I probably didn't save ANY bucks, and the room and bed were horrible.