From bitter experience (due to my own tendency to be "trigger happy" to a large extent) I have adopted a policy of "non-invasive" editing: Edit to refine language, adjust formatting, etc., but refrain from making any substantial changes to the content of any post without the consent (explicit or implied) of the poster. Better to rely on comments and flags.
To act otherwise is perhaps fraught with "moral hazard":
- Nobody can claim complete impartiality - the risk of editorializing
is always there, although it may be unintentional. What one considers a "bad bit" may not be so for others. Having worked as a professional translator, I am all too cognizant of how seemingly innocent modifications and interpretations potentially breed far-reaching "unintended consequences". The question's terminology itself: "questions and answers that are good, or OK, except that they contain some little bits of nonsense or offensiveness" demonstrates that a subjective judgment has already been made regarding the post, even before the editing begins. If so, subsequent edits of the sort under dicussions are danger-fraught.
- Such editing may be the result of misunderstanding the OP's intent.
- At the moment, the policy on SE (AFAIK) is that editors have no
accountability for their edits in terms of reputation: If one makes a
substantial change to a post, they may impact the reputation of the
poster at no risk to their own reputation, although through such an
edit they have "taken ownership" of that post to some extent. IMO
there is some inherent inequity here.
By way of suggestion, perhaps such a policy should be taken into consideration: If a member edits a post that is not subject to peer review, in a manner which effects the substance of that post, the editor in question should bear some accountability for potential impacts on the poster's reputation, perhaps by binding the editor's reputation to that post, to an extent which reflects the degree of their edit.
Admittedly, such a policy would be very difficult to automate, because it requires qualitative analysis of each particular edit within the context of the post in question, and to put such a burden on moderators is not viable.