Often times when the word "really" is used in as an adverb in an assertion or proposition after a word that expresses negation, it may be useful to replace it with "in some sense", and seek to ask or clarify "in what sense". It shall be recognized that questions that arise may be legitimately hard to answer, but it may be still beneficial to consider them.
The same applies for "actually" and similar words when used this way, though in my experience, people tend to use "really" this way.