In the body of the story, there are a few things that will make me race to the finish and not in a good way. I'm not a prude, but if there is a scene that appears out of nowhere that includes graphic sex or violence, I feel like the writer is trying to shock me into liking her story and that turns me off. This is especially true when the scene doesn't forward the narrative or reveal character in any way, but just is sort of a weird aside, like the writer might have possibly have lifted it from another story he wrote in tenth grade and just added it in because he liked it so much
I also don't like stories that end in death--and especially not those that end with the death of the first person narrator (how? why? what?). I don't like stories that end with someone staring off into space, thinking, though I have written those stories often enough.
The ending should be changing something and it can be based on a character's epiphany or decision to think about something differently, but the decision needs to be put into action somehow--it needs to be shown instead of thought about. Two of my stories in my capstone collection need work on the endings. But then in the stories that I've read for the New Yorker lately are ending in the following ways: the woman at her name inscribed ina book, but that's after an explosive encounter with this young guy. Or the dude in the Roddy Doyle story sitting in the dark, believe that his wife will return to him so that they can watch their DVD collections together. Or the guy in "Pending Vegan" having the dog lick his nose at Sea World. These are not earth-shattering endings, but they still feel fitting and justified with what's gone on prior to this last moment.