I've been having issues where someone may paste code from elsewhere into CKeditor, leaving HTML tags open, or including closing tags that shouldn't be there.
I notice that when the view changes from Source to HTML, the tags are balanced. So this happens on load, and when Source is toggled, but not on save.
To see this in action, view Source, enter some HTML with an open tag but no matching closing tag, view the HTML version, view Source - it's fixed.
Even if it means quickly switching to Source and then to HTML, how can I trigger this tag balancing on save?