Before I start reading stories from the On Spec slush pile, the first thing I do is to set up an excel spread sheet so I can keep track of who writes what, where the writer is from (for granting purposes, we have to ensure we have 80% Canadian content), a place for my comments, and how I would rate each piece. As I remove the cover letter, I scan it for biographical info. Today, a small slip of paper slid from an envelope that also contained a cover letter and manuscript. The slip pointed out what we editors might miss regarding the SF content which the writer said becomes evident near the end.
Now, I ask you. If you were a magazine editor, would you need some writer to point out what he thought you might miss about his work? I read the slip of paper a second time. He seemed worried that we might dismiss his story before reading it to its end.
We don't toss work after only reading a few pages. We read almost every manuscript to its finish, unless it is so poorly written that we don't have the stomach for it.
I read his cover letter a second time. He had good credentials. Unfortunately, he also pointed out that he had a sardonic and inviting style.
It's never a good idea to tell an editor how to edit or to pass positive opinions on your style. In the former, some editors might take offense, and in the latter, you might come across as bragging. For me, the work always speaks for itself.