Can a job make someone do certain work way outside of a job description?

My girlfriend works as a sales associate for a small local business, and they recently started having done renovations. They’ve asked her to come in for $12 an hour to paint the walls, clean the rafters, and help with some construction jobs. She feels like the work she’s been doing is outside her scope, and only me and a couple of her friends seem to think that sounds kind of unethical to do to employees. Any advice for her?