Generally, breaking the fourth wall to speak to the reader directly isn't that good an idea; but quite a few good stories are written in a style that suggests the author is a storyteller, rather than simply an observer. For example, C. S. Lewis in The Silver Chair:

"After the meal they had tea, in tins (as you've seen men having it who are working on the road), and Puddleglum had a good many sips out of a square black bottle. He offered the children some of it, but they thought it very nasty."

It's not jarring; and it matches the tone of the story. The problem with author's notes isn't that they break the fourth wall; it's that they do so in a story that hasn't established that this is okay, either because the story is written as though it were being told by a storyteller

The other condition under which I've seen "good" author's notes is in a story that has already established a reputation for fourth-wall breaking for the purpose of humor. I remember, for example, a very silly story in which the author actually interacted with his characters; in that story, the characters heard the author's notes and responded to them. In general, though, that style only seems to match with humor and parody, and can't be used in stories that don't have some significant humorous element.

No, I haven't. But these are good! Thanks for sharing!

That author gets away with it for two reasons: One, it's funny, and two, it occupies a clear space in the text that doesn't distract from the story.

The problem with most in-text author's notes is that they come out of nowhere and distract from the story, often without saying anything useful. The general rule is, if it's really important, it should be included in the narrative. If it isn't really important, it can wait until the end of the chapter.

~Neshomeh, who has never used author's notes except at the beginning of the story on ff.net or at the end in other places.

I used to write in-story author's notes... but after a while I moved on to annotations and end chapter notes instead.

I actually used intext ANs on occasion. Then I came here and found out it was seen as bad form to do so.
So now I'm going to use endnotes instead.