A sad, ugly truth of the veterinary world is that many aspiring vets wash out, having gotten into the job because they loved animals and wanted to help them, only to be confronted with the harsh reality that most of their work would involve having to euthanize animals that are beyond help. This would only be worse in the Continuum's Equestria, given the primitive state of local medicine. Sweetbark is what happens when you take one of these naive animal loving wanna-be vets who would normally wash out and let her keep practicing because she has an alternative - fobbing the ugly work off on poor Fluttershy.
In the 19th chapter, Fleur's reaction to the realization she sent Zipporwhill home with Snowflake is horror, because she hadn't used her Talent to examine Snowflake's fetishes yet, which means she could have just sent Zipporwhill home with a pedophile. She cannot relax, instead burying herself in work to distract herself, until Snowflake returns and she can scan him, proving that he's not attracted to fillies. Just what happened to her to make her so fear pedophiles lurking everywhere? Is it just the Paranoia Fuel of her Talent? Or is it something deeper? Combined with the hints of her Dark and Troubled Past... could Fleur have been a filly prostitute?