A timely question, because I'm struggling with this exact issue today.
I've played ten seasons in a world with no rules. The only thing to keep Tard tactics in check is that the ownership is very stable, everyone "knows" each other and gets along, so the world stays generally free of drama, which is a selling point.
This environment also allows everyone to get real close to the edge of questionable manipulation, without comment or objection. It's all nudge-nudge, wink-wink. Then, when someone does something which steps over what I consider "my line", no one can object because it's either not far from what the last guy did, nor far from something that was done before anyway.
At least once every season, something happens - some owner manipulates a transaction - in a way that ****** me off completely. That's not an experience I'm paying money to have.
So to answer your questions:
Everyone can do something "just once, just this time" in service of self-interest. It takes discipline to realize that your actions only make it easier for the next guy to do more, or worse.
The commish has whatever recourse he decides when he establishes and runs the world. It must be written, stated up front, and he must be unfailing in his judgment.
As for questionable tactics that don't break rules, Mike, you've said it many times, and it's taken me ten seasons to learn the game and understand it - if you don't like the world you're playing in, it's not worth it to stay. Leave, and find a world that lives up to what you want your experience of the game to be.