The logs generated when a docker remote fails are not as useful as they could be. When you do a pull you get a log similar to:
There's a few issues with this
1) It's identical when we've already got the image cached and when the manifest fails to be retrieved.
2) If it fails there's no indication why the failure happened, you should be able to tell if it was an authorization failure or the artifact was not actually there.
3) Which repository is being access is not printed, only the artifact. If you had the same artifact in two repositories there would be no way to tell which one it came from in the access log. You can see it in the request log however.