I'm going to try to make a few things clear about how we moderators deal with posts. When a post by a learner contains errors, we (like other members) correct those errors and, if possible, explain our corrections.
Things change a little when we look at posts from native speakers and, more importantly, English teachers. When we see an error in a post by a non-teaching native speaker or a teacher, the first thing we do is try to work out if it is simply a typo. If it looks like it is, and it's the first time we've seen the error from that person, we tend to use the Edit Post facility and we fix the error on the poster's behalf.
It's when we start to see the same error(s) cropping up over and over in a native speaker/teacher's posts that we frequently choose to draw attention to the repetitive error and, yes, we do that publicly. We also explain that, as native speakers/teachers, there is a greater responsibility to get things right because learners tend to assume that everything teachers write is correct.
We are well aware that there are some areas in which what might appear to be an error to one person might not to another. There are variant/dialect differences, there are grey areas (like the use of hyphens in some contexts), there are even some generational differences. There are, however, errors that are simply errors, no matter who makes them. For example, any deviation from the oft-repeated list of "rules" (below) is considered an error.
- Capitalise the first word of every sentence.
- End every sentence with one appropriate punctuation mark.
- Always capitalise the word "I".
- Do not put a space before a comma, full stop, question mark or exclamation mark.
- Always put a space after a comma, full stop, question mark or exclamation mark.
- Don't put a space either side of a slash mark.
- Don't put a space after opening quotation marks or an opening bracket.
- Don't put a space before closing quotation marks or a closing bracket.
Whenever native speakers/teachers repeatedly fail to follow those rules of written English (which apply, we believe, to all variants of English), we have to draw it to their attention. If they continue to make those errors, we have to consider whether their assistance on the forum is truly of benefit to learners.
We are equally well aware that any member is free to draw attention to any error made by a moderator.
We have one main aim on the forum - to teach learners grammatically correct, natural English. Let's remember that.