The big thing with approvals and appeals is what I call the C/C- effect; Imagine if every post had a letter grade rather than a score or such. Andsay the standard for Danbooru was to only accept posts with C grades or better. So far so good.
But letter grades for tests are usually based on hard numbers; You get a certain percentage of questions right, you get a certain grade. With post quality, as has been stated many times, quality is subjective. Now we can assume that most people can agree on a general range of where a post might be graded, plus or minus a grade; If someone thinks a post is an A, then likely most others will at least have the post as a B or better on their own scale. This means a B or A will get approved nearly 100% of the time, as even the most critical person will think they fit within standards. B-'s or below face a dilema though; The natural range of opinion means some people will think they're not approval worthy while others will. And this divide just grows greater as one goes down to C+ then C.
Here's the thing; Few people want to approve something someone else might see as a C- or worse though, no matter what they personally might grade a post. Anyone who's been here long enough knows how critical people can be of people approving subpar posts. This is exasperated by approver promotion and grading being dependant on how few subpar posts they like/upload/approve.
So what happens? Obviously, almost no one wants to approve posts with a B- grade or below, whether they think they might be good enough to approve or not. And things on the C side of the C/C- divide? Finding domeone brave enough to approve those gets really tough. Especially since thete is every chance you're actually "wrong" about it and it's "actually" a C- to most people.
Ultimately, the whole system simply rewards this; Those who approve fewer posts. with higher scores, while stay away from borderline cases are safer in their position, safer from criticism, and scored higher in any metrics or reviews.
This all comes back to feedback in the moderation process. Giving a reason to think of something as a C- rather than a C is really fiddly, and just as much personal opinion as a codifiable reason; And it's such a grey area that agreeing on the reasoning will be tough regardless, unless you're pointing out glaring reasons why something should be a D or an F. Plus, with the system as it is, just as often I'd imagine there is actually little reasoning beyond the simple fact that taking a chance on too many borderline cases just isn't good practice, with the way things are.
I can't imagine there are any easy solutions of course.
My personal opinion; Rewarding people who are brave enough to approve or upload C's would be nice; The current enironment of "Err on the side of caution" (to quote the upload guide) just incentivises people to not approve or upload C's in the future... and then the bar is simply unofficially moved to C+'s and that becomes the new borderline that people are afraid to upload or approve. And really, anyone would be willing to upload or approve an A quality post, so someone doing so shouldn't really be seen as much of a stretch or an accomplishment.
That said, I understand that no one is excited to see C quality posts, to see images just good enough to be approved. And one can't just actively reward or encourage the posting and approval of C quality, because even if the line is fuzzy there's obviously a line between those C's and C-'s there somewhere. And Danbooru is Danbooru, in part, because it has higher standards than the Gelboorus and Rule34s of the world. But then, Danbooru wouldn't be Danbooru if it was all A's either.
Regardless, I certainly don't think a lack of moderator views or a lack of given reasoning are the root of so many peoples' troubles, going to appeals multiple times and getting frustrated. A fuzzy spectrum system (good to bad) with a binary result (approve or disapprove) will always have that. I simply think an environment where deleted posts aren't as much of a stigma (both in the minds of mods and those participating in the upload/approval process) would be a nice way to approach the issue from a different angle.
