One of the most difficult duties of a healer is masking one's criticism when expressing it would serve no healing purpose and when it would discourage further communication.

I'm certain I've failed often enough in this regard. And I'd wager that most healers struggle to master it.

I gather you didn't observe the treatment Hydra received?

Do you know, instead, whether the spilt blood and tissue were promptly scourgified and vanished? What appeared to be merely blood might be easily analysed if someone had thought to collect a sample. And, of course, there are other uses for samples of spilt blood and she'd tissue.