Unwanted hyperlinks containing 'msocom1' inserted into my WordPress content
As mentioned in comments, this would seem to be the result of pasting content from Microsoft Word. Perhaps where the original document contained embedded comments - "msocom" - MicroSOft COMment.
Comments in this WordPress ticket/thread would seem to suggest that MSWord tries to convert the comments into linked footnotes in the resulting HTML. There is an example of pasted content and the resulting HTML which contains #_msocom_1.
Also discussed in the linked document is a recent update to WordPress/TinyMCE to "fix" issues of pasting content from Word. A lot of users do seem to paste content from Word (which has historically always been problematic), so this could go a long way to explaining why there are "so many unexplained examples on the net".
Expounding on w3d's answer: From the look at the # sign this is the tell tell sign for a Div ID. To verify this export a Word document to HTML. Newer Versions >=2003 will insert CSS Markup to try to match the look of the document in the <head> tags. This includes Fonts and Paragraph Spacing. The reason all of this looks like Garbage in WordPress is because the CSS for the <div id> tag cannot be inlined due to the way PHP renders the page. For this to work correctly, you must dissect the word document and copy the CSS into the appropriate file for your theme. In WordPress, that's the Admin Menu > Appearance > Editor Submenu.
The easiest way around this that I've found, is to tell Authors to copy from Word to Notepad, and then from Notepad to WordPress.