Before you include such information, you will need to evaluate it very carefully—because you will eventually have to convince an editor that it is trustworthy and worthy of inclusion. Ask and answer these basic questions: (1) How does the source know this information? (2) Does he/she have a reason to lie or color the truth? What do they have to gain? (3) Do you know the source; have they provided you with information in the past? (4) Does their information “fit” with what others are telling you? Can it be substantiated? (5) Can the facts/information they are giving you be interpreted in any other way?
The questions may vary with each different scenario. If you doubt your sources credibility, your editor and ultimately your readers will too. Trust your instincts—then get a second opinion from someone who has no vested interest in the piece and who’s judgment you trust.
If often comes down to your personal tolerance for using anonymous sources—some writers choose never to use them—and your editor’s (who also may have strong feelings about it). In many cases, using an anonymous source is like sending a nasty letter without signing it. Ultimately it is a matter of trust—your trust in the source—the editor’s trust in you—and the public or reader’s trust in the publication. So use the anonymous source only when you have no other way to deliver the truth.