The current guidelines for editing are very scarce. I would especially like to know the actual consensus on the philosophy of editing the answers of others.
We welcome all constructive edits, but please make them substantial. Avoid trivial, tiny one-letter edits unless absolutely necessary.
fix grammatical or spelling errors.
clarify meaning without changing it.
correct minor mistakes.
add related resources or links.
always respect the original author.
this site is collaboratively edited, like Wikipedia.
Point 1 is incompatible with 2 and 4. The vast majority of questions and answers that require corrections for clarity or spelling are going to range from trivial to small and affect a sentence or two, without risking conflict with point 6.
Point 1 is fundamentally incompatable with 3, 6, and very likely 5. Real "substantial" edits to improve the quality of a question or answer are almost guaranteed to modify meaning, especially if they involve correcting factual or coding errors. Additionally, important coding corrections are likely to appear "unsubstantial".
Point 7 (from the FAQ), from what I gather is a very bad analogy. Per the previous bullet, the types of edits that "boldly" modify content are discouraged, sometimes even if unambiguous and indisputable (e.g. coding errors again). This makes stack overflow very unlike any other wiki in which the goal is to collaborate in order to make a page or article as good as it can be.
Point 5 seems rarely exercised in practice. Doing so especially with accompanying text, again, often entails modifying meaning. Adding links or resources is usually done in comments.
Personally, I don't see the point in whitelist-only heavily filtered editing. Why can't it work like most wikis where if an original author disagrees with an edit, they can simply revert or improve it themselves? Things naturally work themselves out except in the case of comparatively rare edit wars requiring intervention.
Public forums like S.O. where editing is impeded run the risk of succumbing to what I call The W3Schools problem. That is, the most popular resources with high search rankings and containing information that appears plausibly correct to the non-expert can be, and often is dangerously flawed, and can spread misinformation to the masses for years if nobody is allowed to edit them. Respecting the original author means leaving critical mistakes intact in answers clearly written and upvoted without adequate research. The positive impact I can make by downvoting or leaving a comment is limited especially if the author disagrees, and the current reputation system gives no incentive to this important task. The most constructive types of edits, i.e. those that improve the accuracy or completeness of an answer, are sometimes unwelcome.
But that's just my initial observation. The main point of this question is that a philosophy should be decided upon, made clear in Policy, and enforced consistently. The FAQ in particular says almost nothing about editing philosophy other than that questions and answers may be edited, leaving new users to guess.