There is an established mental health disorder with the name "Borderline Personality Disorder." This label has its critics. See also here.
First, the category itself is questionable, because it is so often co-morbid with other conditions, doesn't have a fixed core of symptoms found in every person given that diagnosis, and is often confused with conditions like bipolar disorder, which can present similarly. It is a muddy diagnosis that may not have a common cause or a common suitable treatment that fudges inadequacies in the diagnostic system.
Arguably, this is a feature and not a flaw. Nobody in the clinical community is claiming seriously that people who are diagnosed with Borderline Personality Disorder by qualified psychiatrists who are doing their job properly do not have a mental health condition. Once one is diagnosed with "something," the specific treatment plan may be rather ad hoc in any case, tailored to what works and the individualized presentation in the patient. Ambiguous muddy diagnoses prevent someone who clearly has something wrong from falling through the cracks because they don't fit in a specific box.
But, the lack of coherence in the category does illustrate that the modern psychiatric medical establishment isn't really sure what is wrong and doesn't really know what to do about it.
Second, the label has pejorative connotations, seems to be applied to women when men with the same symptoms would be given another diagnosis (often "psychopathy" or in DSM-IV language, a particular subtype of "anti-social personality disorder"), may capture clinician bias about a particular patient rather than objective symptoms, and it isn't really clear what metaphor is being invoked when the "borderline" label is used - borderline between what and what? Critics argue that the label essentially consists of being both crazy and difficult, rather than merely crazy, or merely difficult.
Now one can argue that any classification that carries as diagnostic criteria more of the folk definitions of "evil" than all but one or two other diagnoses is inevitably going to develop prejorative connotations, just as labels for people with low IQ have to be re-invented every decade or two because they inevitably develop those connotations and cease to have exclusively clinical meaning.