Because some uses are okay, people often ask which uses are okay. Such questions often miss the point. The most important risk is not of liability , it is of suit. Still, it is much better to work from scratch. Things represented to be in the public domain may not be.
Litigation is expensive.
People concerned about, say, the nuances of fair use must not become so entangled in legal details that they forget that anything generating income or interfering with another's potential income dramatically increases the chance of suit. All rights reserved.