Subversion vs. Failure
A subverted trope is one that is consciously inverted to produce a specific effect. A failed trope is one that was attempted and did not land. The difference is author intent, execution, and signaling: but readers cannot see intent, so they read execution and signaling. A book that subverts the romantic happy ending without clearly signaling to romance readers that this is the book's intention will be reviewed as a book that broke its promise. The subversion must be visible in the packaging, not only in the reading experience.