To me, there aren’t many bad recordings. I think objective “good-ness” and “bad-ness” can only adhere to sound quality and playing/singing, and just about everyone can play Mahler well these days. They’re just different from one another. They’re all adhering to the same score, and they all have their own artistic spin on it. If we are judging who interprets the score most accurately everyone ought to just give up and go home because Pierre Boulez already recorded a complete Mahler cycle.
I am curious to hear why you think Zinman, Stenz, Bloch, and the Fischers have bad M7s, because if you’re comparing them to the approaches of Ozawa, Solti, Haitink, Bernstein, et al., of course it’s going to be “bad,” because it sounds nothing like them. The newer lads aren’t even trying to sound like the old greats. Perhaps they’ve inherited some ideas, but they aren’t mindfully competing with the conductors of the past. I’ve said this before in different context, but I don’t believe as Bloch was performing and recording his M7 he was thinking, “we need to do better than Bernstein and Solti... at all costs!” No, Bloch is making his own artistic statement on the work, not trying to compete with past conductors. With Bloch what I hear is a French approach to M7, something VERY unique for Mahler recordings and different by default from what we get from the old greats playing from the traditional Germanic or American approach. If Bloch’s textures sound more sparse and less heavy, remember that this is a French conductor and orchestra. That’s how French classical music sounds.
I’m not trying to start any arguments here. I’m just saying that everyone’s likes and dislikes are valid, but is a recording objectively “bad” or “good?” I find it very hard to back that up with factual evidence outside of sound quality and playing/intonation. After all this is music, or art, that we are talking about.