Three will simply have to be returned. Even an editor may not know all the things that go against one manuscript in favor of another. A story sent single-spaced, for instance, quite obviously has a large strike against it before it has been read. But not everything is so conspicuous. And many an author may have had the scale tipped against a story due to something so small that it shouldn't have been an issue.
Authors do lose sales due to trivial blunders.
The reasons aren't always entirely fair, but there they are. Happily, most of these blunders are easily avoided once they're understood. These may well cause me to stand in a long post office line to sign for a submission, leaving me less than delighted to have received it. A magazine editor once told me that it was his opinion that anyone who registers manuscripts is a paranoid who will end up accusing someone of stealing his cliches, so it is a good plan never to open such a submission. I share that policy.