Mulgrew was the one that first started me thinking about this topic: there simply are no "wrong" notes. One of the things that Mulgrew excelled at was making "wrong" notes sound right. It simply has to do with the context in which you use these wrong notes; i.e., the notes and phrases you surround the wrong notes with.
This is hard to verbalize!
Of all the tribute statements flying around the web now, one that resonated with me the most was said by the late James Williams. Speaking about Mulgrew many years ago, James said "He is the state of the art in jazz piano playing."
RIP Mulgrew.
George Z