In some evaluations, we determine that a standard or feature may have some merit, or be mostly good, but discover that it does have some harmful aspects. Since we think the problem being solved is user-relevant, and perhaps may even agree with the approach, we avoid marking these as "harmful", and end-up averaging down to "worth prototyping" (i.e. with actual concerning caveats, beyond just clarification or bugs that need fixing), or "non-harmful".
For example, I would have advocated (and I believe we would have stated) in https://github.com/mozilla/standards-positions/issues/194#issuecomment-568581041 that that spec is "mixed" rather than just "non-harmful".
Per @bholley’s comment in 242, ironically, averaging "worth prototyping" (or "non-harmful") and "harmful" down to "non-harmful" seems itself potentially harmful due to the risk of the position being misconstrued as being more positive than our evaluation actually states in prose.
Proposal: add "mixed" with a description like:
Our evaluation of this specification is mixed, meaning while we may otherwise consider the majority of this work neutral (non-harmful) or positive (worth prototyping, important), we have identified specific actually harmful aspects (beyond just bugs or underspecified aspects that need clarification), that require resolution before we can place a neutral or positive summary status on it. If there are many harmful aspects that seem endemic to the design or approach despite a specification’s good intentions / use-cases, then "harmful" should be used as the status. "mixed" does not mean just any mix of statuses, but rather specifically a mix of "harmful" and another status.