I recall a certain Word document which had some "interesting" history, but hidden from view for Word users.
I forget what protection was in place, but dropping it onto a non-Windows O/S and dumping the raw contents of the file revealed all, in clear text.
I company I worked for sold access control systems that had a database on the PC. Open that database up in Wordpad, do a search for Admin, right next to it was the password in plain text!
To be fair, they did change that rather quickly!