Embarrassing or personal questions may be phrased in a less threatening way by involving a third person. For example, instead of asking “Do you think the raise is fair?” the supervisor can ask, “Do the employees in our department think the raise is fair?”

You have to listen carefully to the answer to determine whether they reply using their own personal opinion (as is often the case, and is really what you are after.) You may need to ask some additional questions to more fully flesh out the information you are looking for.