There are extremely rare situations where not naming sources would be appropriate, for example, when the person giving the information might lose his life , or when the un-named source backs up a named source. An un-named source should not be used to confirm basic information, or used as the only evidence. If you can't confirm what an un-named source is saying, you should not use it, simply put, if your not giving us your name, you best be giving us something else besides your word. now off the record or background is fine, if its used to do some real investigating, but most of the time, they should not be the meat and potatoes of your story... hell not most of the time, never.