Editing anthologies is a very instinctual skill for me, not something bloodlessly objective. It may not be that way for others.
For me, it has its analogies to the way I write. Just as I feel my way into a short story I'm writing through the texture and tone of the language, so too I feel my way into a story I'm reading for an anthology--if the story allows that to happen; if it doesn't, I know the story's not for me. If the language is blunt where it should be subtle, or subtle where it should be blunt; if the choice of words does not in some way reveal care with language, then I cannot sneak my way beneath the story's surface, and I know it's not a story traveling anywhere I want to go.
Just like with my writing, I take certain things on faith. Sometimes I do not fully understand why I made a choice I made in a work of fiction. Eventually, it becomes clear, but not always right away. The same thing often occurs when reading for an anthology, in that sometimes I will not immediately understand a story but still feel that it is right. That the story has integrity and makes internal sense, even if that sense cannot immediately be extracted from the story. In extreme cases, where the story's structure and language are so perfect, if oblique, that it feels as if the fault is mine not the story's, I may take a story I still do not fully understand. Ursula Pflug's "Python" in Album Zutique #1 is a good example of a story of this type. Not until after I read it in the published form did the story finally make sense to me.
Am I crazy to take a story I don't understand? On some level, perhaps the answer is yes. But I have a great faith in the subconscious workings of the mind, and when you feel something is right in your reptile brain, eventually you will know why with your conscious mind. The other factor is that I feel impoverished, starving, if I read too many stories where I understand everything right away. Either it is a failing in the story or in me, in such cases. To only come to the full meaning of a story late, and after several re-readings can indicate a story that fully deserved one's repeated attention. (Of course, it can also mean the story failed.) When we predominantly think of the story as "entertainment," we deny the ability of a story to get deep into our souls and burrow there, to take hold of us in unexpected and stunning ways.
Another way in which editing anthologies is like writing fiction, for me, is that I always want my reach to exceed my grasp--only in that way can I continue to grow and improve. It leads sometimes to failed experiments, it leads to utter catastrophe at times, but it also means you travel farther than you would have if you'd tried for less.
For this reason, anthologies I edit are almost always going to be baggy, thick, confrontational, multi-faceted creations. I'm always going to take stories I think push boundaries, for better or worse, whether readers or reviewers ultimately think that the results are not always successful. I don't suggest this is a better or worse way of editing than other approaches. I'm not advocating any kind of semi-mystical approach, either. I'm just saying that this is one of the only ways to really push yourself.
There are thousands of replicas out there that don't realize they are replicas. Why knowingly be one of them?