Pink skin was an Andorian slang term for Humans, in reference to the "pink" skin color of some of the first Humans that they had encountered. It could be a derogatory, neutral, or even polite phrase, depending on the context in which it was used.
The phrase was used many times by Shran and once by his daughter, Talla. (ENT: "The Andorian Incident", "Shadows of P'Jem", "Cease Fire", "Proving Ground", "Zero Hour", and more, "The Aenar", "These Are the Voyages...")
In 2369, the Ferengi bartender Quark noted that Chief Miles O'Brien's face got very pink when he was aggravated, much more so than most other Humans. (DS9: "Captive Pursuit")