> That's not detecting "announcers", but maybe more like detecting "indexers".

I think you’re correct, as the secondary freebooting indexers are adding their tracker(s) after the fact of the private torrent’s creation/origination to the original prefilled list of trackers, and inserting their tracker(s) to the reuploaded, usually public, torrent, and sometimes even removing the original private trackers so as to not phone home and tell on themselves.

I’m happy to be corrected, but private trackers typically bind the downloading IP of the torrent to the announcing tracker to validate legitimate clients. Private trackers don’t consider any extra trackers (announcers in this context) as valid or authorized. I have heard that modded BitTorrent clients can intentionally misreport upload stats to fudge the numbers for gaming your quota, as many private trackers/torrent sites enforce a positive >1.0 or higher minimum ratio.

I’ve heard of ways that folks with legitimate access to the private torrent tracker and torrents clone the IPs of other clients and then use a secondary torrent client to request blocks, bypassing the tracker entirely and not reporting any downloads (or uploads, for that matter), so the quota of the first legit client is not affected positively or negatively.