The issue of rejections has circulated in a few blogs of late. As a teacher, I can't help but see the similarity between the role of editor and that of teacher.
While studying for my education degree, I took a class on methods for the language arts (English) classroom. One of our liveliest debates centered around how to provide feedback on student writing. Some were in favor of as much positive reinforcement as one could provide. Others felt that only constructive criticism should be offered--we were future teachers after all. Still others thought that a grade was enough: let the student know how they did, and then they can sort out the mess later--in my opinion, those individuals needed to seek other forms of employment.
Although it isn't the job of editor to teach, some do. Some don't have the time to. (I can't imagine personal feedback for every story rejected at Cemetery Dance). Some pile on the positive with "not right for us" tacked on at the end; some leave us with constructive criticism. Others simply give us the grade and move on.
I've had rejections that made me feel better, in some ways, than simple acceptances that left me wondering what they liked. Tim Manning at Black Ink Horror writes some of the best rejection letters. Of course I always prefer acceptance.
I'm indebted to those kind editors who took the time to provide some constructive criticism. I also try to be understanding when they don't. Ultimately, the editor is not bound to provide a detailed explanation for a rejection...but, like the best teaching, it can be a fine gift when they do.