One of the hardest things about putting together demos of software is creating interesting and useful dummy data. When I wrote about how I use plain text for tasks, I was torn between having fun with the dummy data and not wanting to get sued by someone. It's a lot of work to create a fully realized set of data and it's even more work when it's mind numbingly boring.
Here's a nice summary by Mark Fowler (which I reviewed with someone trained in the subject).
So can I have Don Draper make a cameo appearance in my novel? As you can see, the answer is a thoroughly equivocal "it depends."
I see a lot of people taking liberties with things like podcast intro music or re-purposing prose for articles. I like to think it's out of ignorance for the laws surrounding copyright. Unfortunately ignorance is a poor defense in a courtroom. As with most copyright conflicts, it's going to come down to deciding if you have the money and will to fight. At least know what you are up against. I'm not providing legal advice here, because I'm not an attorney. I hope I'm providing common sense.