Publishing in a non-paying market, which I assume this is, puts something of a stigma on a story -- the idea being that if it were any good, it would have sold. And yet, there are many examples of great stories that were rejected repeatedly -- Lois McMaster Bujold's Shards of Honor is one example. And a lot of the stuff published in paying markets, and even in Best of the Year anthologies, is crap. There are a few stories that are so good no editor in his right mind would reject them. John Varley's Press Enter comes to mind. Then there are a large number of stories that are ok. Professionally written, interesting plot, good characters. There are more of these than the professional markets can handle. And so the editor's taste, whether or not the editor and the writer are drinking buddies, even which side of the bed the editor got up on that morning, will decide whether or not the story sells.
On the other hand, there are many, many more published stories, even if we limit ourselves to paying markets, than anybody has time to read. I think most people start out reading almost everything, home in on a few favorite authors, and stick with them over the years, adding a new author only when that author develops enough of what Samuel Delany calls "markers" -- good reviews, interviews, awards, and word of mouth comments.