In the Yiddish Chofetz Chaim (red cover), its page 129 (Hilchas LH, Klal 3). He says (not quoting word for word):
LH is Assur even the words won’t lead to damage (in whichever from), either because a)the listeners didn’t believe b)the listeners “didn’t get who’s being discussed”. In short, the persons identity is not revealed. He then brings down a Rbainu Yona which explains the concept in details.
So there you have it. Now, you guys understand that you are probably sinning far greater than the girl with the Treif chocolate who we don’t even know whether she a)ate the chocolate b)bought it for herself (etc etc, but basically, being Dan Lkaf Zchus)