I can relate. Hear me out.
When it comes to good vs. bad, music is subjective. Mixing is subjective. Drum sounds are subjective. It’s all fucking subjective.
You have to accept this or you’re going to keep driving yourself crazy. It’s not bowling, where a strike is a strike. It’s art, where sometimes, somebody paints a red square on a canvas and people drool over it for some reason. What you’re producing is always art. You have to remember that, and not try to turn art into something objective.
That being said, an artist has many tools at his disposal. With mixing, you have your ears. You can train them to hear subtler and subtler differences in sounds. They’re still just a tool. And then you have your engineering skills. You know what plugins do what. You know how to use them to change the sounds. You get faster at this as you go. Less experimenting and more precision. These skills can only be practiced and measured on their own, though. You cannot use a final mix in order to gauge these skills. This is the objective part. Are you improving at TrainYourEars software, or whatever kind of other ear training? Are you knowledgable about your software? If someone said, “make this vocal less harsh” would you know how to do it? If someone said, “I don’t want the guitar to stand out so much,” would you know how to do it? There are countless examples. You can train these things, and you can measure your improvements because they are measurable.
When it comes to a final mix, you are in the realm of art. Stop looking for validation when it comes to your art. That’s a black hole and you will drive yourself crazy. It’s wonderful to hear other people’s opinions. They can give you new ideas, or maybe provide a little extra weight to a hunch that you already had. They might have opinions about how good it is. But they CAN NOT tell you definitively how good your art is. Not even the best mixer in the world, or a whole panel of them, can do that. You have to do that for yourself. You have to know whether or not you like a mix. You have to take that responsibility back for yourself. You have to own it.
I think that if you can differentiate between skills and art, you’ll have a less frustrating journey. I hope this helps. I can use this advice myself, to be honest.