I've often heard people say something like, "Someone was talking during davening today" while being careful to avoid naming the person. From here I might guess that it is not considered lashon hara if the person is not named. Is this correct?
If so, how far does this extend? May one say something bad about "a member of the Goldstein family" (where there are only a few possible people)? What about saying, "Either Reuven or Shimon did [bad thing]"?
Suppose there are three relevant people. Can someone say that two of them committed a sin, so each person now has a 2/3 chance of being guilty (although no one is definitively faulted)? If so, what about discussing the sins of "everyone in shul except one person"?
In short, may one say something negative about an unnamed person? If so, where is the line drawn?
Please provide sources.