You'd be surprised how many times people will leave something like that in the open. When going through an office building and passing by the cubicles, 7 times out of 10 you'll see a note hung up with the person's username and password. Sadly this isn't even hyperbole. I've seen this sort of thing myself and have taken network security courses which touched on this vulnerability. Keeping their info safe is something most people dont give a second thought to unless something happened to make them be more wary.