This is not surprising, and it's not that uncommon.
There are multiple reasons for this.
1). Heading the list is subjective criteria. I've harped on this enough, and I think we understand that it is hard to keep a category totally objective. But, it inevitably leads to this type of inconsistency as differnt people apply their own judgments.
2). Unclear or ambiguous descriptions/posting requirements. Some categories that come up for peer review suffer from this, but there are existing categories that still leave one wondering exactly what is or isn't accepted. If the guidelines are unclear to the waymarking, they may also be unclear to the group officers who are reviewing the waymarks!
3). Different philosophies among the officers. Ideally the group leader should set the standards for evaluating waymarks. Unfortunately, many categories lack a true leader, either through attrition or intention - or neglect. So, everyone feels free to apply his/her own standards and interpretation, or just personal preferences, when reviewing waymarks. Some tend to be generous in accepting waymarks, while others are strict, or even nit picking. As long as we have group management, there will be inconsistencies in the review process, despite our best efforts.
4). Bad day at the office. Let's face it, if the reviewing officer is stressed out, rushed, or otherwise impaired, there may be inconsistencies even with the same officer's reviews. It can work the otherway, too, when one is in a good mood and everything, even a bad waymark, looks rosy.
5). Mistakes. Sometimes a reviewer just may miss something, interpret someting wrong, or missapply a category requirement. I've sure done this a few times. Usually a nice note on resubmission pointing out my error does the trick.
No one likes haveing a waymark declined, and I think most people who review waymarks don't like declining them. I've had my share of declined waymarks - often with good reasons (I've done some really dumb things on waymarks). Still, there are those that could, and maybe should, be disputed. I recently had a waymark accepted, and then a few days later declined by another officer who misinterpreted the waymark which fully met all of the requirements. I was upset, and he was upset that I was upset, and so . . . Well, we'll just have to allow for the fallible human element, won't we?
Sure understand how you feel, though.