I've been editing a provocative nonfiction manuscript that contains some ideas with which I agree, some with which I disagree, and some with which I disagree strongly. The author has expressed concern that in the process of editing his work, I may inadvertently or purposely alter his meaning due to its controversial content. This is a reasonable worry for any author to have when handing his manuscript over for edit or critique.
I've been on the receiving end of revisionist edits and notes which were based entirely in matters of the reader's personal sensibilities, and it's an experience that's annoying at best, downright offensive at worst. Imagine having your independent, feminist protagonist watered down by a reader who feels such traits are unattractive in a woman. Or getting the note that there are too many references to liquor and bars from a reader who happens to be a recovering alcoholic. Such notes aren't helpful, because while they demonstrate very clearly how to alter the manuscript to better suit one specific reader's tastes, they don't offer any guidance on how to improve the manuscript in a way that will make it more appealing to the general public.
Editing and critiquing demand judgment calls from the reader, but it's a very narrow kind of judgment which should be based only in matters of linguistics and literary form. For example, it's fine to suggest the author eliminate a lengthy passage of navel-gazing on the part of the indecisive protagonist because it brings the story's pace to a crawl, but it's not okay for the editor to make the same suggestion merely because she has no tolerance for indecisive people in real life.
It can be a very fine line to walk, because the nattering observations of an indecisive person truly will seem to bring the story to a crawl for a reader with no patience for such people. But it doesn't mean a reader who doesn't share that particular pet peeve would suggest the same change. This is one of the many reasons why authors should seek out multiple reads from different people, and one of the many reasons why those readers should approach their task with self-awareness and humility.
In the end, matters not specifically pertaining to rules of grammar, spelling and proper usage are all matters of opinion, and this is something authors, editors and critiquers alike should never forget. What one reader finds distasteful, another will find fascinating. What one finds boring, another will find lyrical.
For authors, the trick is to work toward some kind of majority consensus. For editors and critiquers, the trick is to remember that their proper role is merely to bring the author's vision of his ideal manuscript into sharper focus, not to alter it, editorialize on it, or make it more closely resemble whatever vision the editor or critiquer may have in his own life or philosophy.
So, while I may not agree with an author who says [insert viewpoint to which you are strongly opposed here], it's still my job as editor to ensure his message is communicated as clearly and forcefully as possible. If I've done my job well, by the time I'm finished I will have helped the author win some converts to his cause---just as I've been won over to various causes by well-written treatises. And if I have a problem with that, I shouldn't be editing his manuscript in the first place.