Yes. That is my point. You cannot automatically assume the person is black based solely on the description "darker complexion."

There are plenty of races that include darker complexions that your average American wouldn't consider black even just looking at them (e.g., Indians). There's more to looking black than just skin tone, there's facial features, hair type, etc

The word anxiety existed long before the clinical concept of an anxiety disorder and it did originally just mean nervousness or a troubled mind, so that casual usage is totally valid.

The first time dissociation was used to refer to a mental state was in the 19th century and it was considered a kind of hysteria. Casual, nonclinical use of the term is very recent.