Being a professional writer (of both fiction and non-fiction) and editor of all kinds of work, there seems to be a repeating theme amongst an alarming number of fellow editors and writing reviewers: this need to become overly emotional with their editing and feedback.
The sheer amount of edits I get back from beta-readers looking at my upcoming novels with comments that are inches away from aggressive abuse startles me! I actually laugh out loud at how emotional some of these editors can be and, truth be told, it can actually lead me to distrust and undervalue them as you begin to question their thought patterns and motivation behind their processes.
Now, I'm NOT saying that I don't have a thick skin or anything as petty as that; this is NOT a whinge blog post. In fact, the deeper and more thorough the reviewer and editor is, the better in my opinion! However, there is no need to get aggressive or emotional with your edits, notes and comments.
As an editor: keep your comments professional. It's very important that if you are dedicated to your craft and are serious about repeat work, and wish to encourage positive word-of-mouth about your services, you ideally want the original author to continue to trust your opinion. There is no need to capitalise your comments (e.g.: "DO NOT USE THIS WORD HERE!!"), use excessive punctuation (e.g.: "Why would any character ask this?!?!?!?!?!?), or use snide comments (e.g.: "Surely you know this is wrong?!").
Editing work is already a sensitive process, as people are very defensive with their work, so I believe it best not to poke the wound by adding unnecessarily bitter comments.
I prefer to keep my editor comments light and informative, without emotion. Professionalism is the key as you want the author to read your ideas and comments, and think to themselves 'Yes, I see why you would think this.'
Additionally, give them the option to agree or disagree with you. After all, it is their work and most elements of writing are very subjective; ie: your opinion may not always be correct.
When editing, I try and keep suggestions light, as one of the main rules to editing (especially with fiction) is not to rewrite it for the author; instead, explain why something did not work, or give them your opinion from the perspective of a reader, not a writer.
Remember, as an editor, you're there to help, not patronise!
All the best in your writing endeavours!