while I don't have any reason to doubt what you guys written above , surprisingly perhpas, my experience doesn't support those assertions. At least when comes to boys gossiping about their former clients to their current ones.
Over years I had many encounters with guys who were entertaining previously my friends and they knew it. Still I recall only one case when they shared piece of information which could be possibly considered compromising and even that was not exactly very specific :" your friend likes to fuck right away " , that was comment when I asked guy if he wants to drink something. Since boy was / still is versatile and I have no idea what my friend's preferences are , that was not much of a gossip I guess. All other cases - complete discretion, including few occasion when encounters were of " when you guys are done sent (insert boy's nick) to my room #312 " kind.
It would never cross my mind to ask boy about this or that related to somebody I know, perhaps that helps to keep things in the shadow.