This morning I came across an excellent blog entry about rejection letters from someone who actually goes through slushpiles herself: http://nielsenhayden.com/makinglight/archives/004641.html.
Enlightening stuff. I found para 3. The context of rejection, particularly interesting. It contains a list of 14 possible categories your manuscript will fall into. I think it applies equally well to short stories.
Teresa makes an interesting point at the bottom of the list:
'...Aspiring writers are forever asking what the odds are that they’ll wind up in category #14 [buy the book]. That’s the wrong question. If you’ve written a book that surprises, amuses, and delights the readers, and gives them a strong incentive to read all the pages in order, your chances are very good indeed. If not, your chances are poor.'
Great advice. I wonder if we could persuade agents to jot the relevant category number on the top of their query responses. On second thoughts, do we really want to know?