alt Hacker NewsThe proper way to cheat is to not leave a trace on the tracker where a tracker staff may or may not make correct judgement. It's called "ghost leeching." Basically you directly connect to known peers' IPs (e.g. from some heavy seedbox users) and never even report anything back to the tracker.
Of course, those peers where you ghost leech of then would correctly report the upload they generate (making THEM look suspicious of cheating by "over-reporting" upload.) It's impossible for any tracker staff to properly detect and attribute proper cheating in such cases, unless they can detect a pattern. The tracker staff objectively can only catch people that do really stupid things.
That's just the way BitTorrent and private tracker economics work. A "private" tracker is more like a social contract between its users to do the honourable thing, but you'll always have some idiots that do not get that, of course.
The limitation with ghost leeching is that it won't help raise your ratio. It's a way to avoid decreasing it (by never reporting download). If your ratio is bad and for reasons you want to increase it, you will have to generate upload one way or another. You can ghost leech and then seed the torrent you downloaded, but it can also look weird that you are now seeding a torrent that you never downloaded. But due to the nature of torrent, it is also possible.
But that's what I find fascinating. BitTorrent is a very cool tech, and not that hard to understand. It uses a lot of simple idea that works very well together. It's really fun to hack on it. And I add an obsession with findings 'cheating' methods a few years back. Overall, as you said, it's more of a social contract. None cared unless it was stupidly obvious.