You do get used to the smell, and it does fade in your senses. I used to notice it when I'd been on annual leave, the first day back always hit me and I'd think "wow it smells!"
But the fact is, as an 18 year old, if she wants to pursue a career in direct healthcare (that is care assistant, nurse, doctor, paramedic) straight out of college, then she will have to become accepting with dealing with poo, vomit, urine, sputum, blood, genitals, breasts, and death, including dead bodies. Because that's what it's about. People, at their most vulnerable, in their hour of need, who generally need you to deal with any or all of the above.
I would say the same if she wants to be a physio (chest physios deal with sputum day in, day out), because physios can't just leave people to sit in their own poo/wee if they find them that way when they attend to give therapy, and often end up helping with turns, sheet changes, etc.
Similarly, speech and language therapists deal with sputum and vomit frequently, as they do swallow assessments and food challenges.
Occupational Therapists do masses of functional work, which involves toileting, walking, etc.
You really can't escape it. If she wants in with healthcare, she needs to dive in and pinch her nose. Or, she may just have found out how much she wants it.