I'll give you two examples and I think both work.
MGraham - we have fairly well-defined rules of trade. We also have a screening process that requires experience. The rules are pretty lenient, BL-quality for BL-quality, current or future, without a ton of cash. Essentially, if you can make a case for a player being on a playoff roster, he's BL-quality. This allows owners to dump salaries and "win" trades. Works pretty well. But we had a problem. An unsuccessful owner made a deal that, quite frankly, he lost. It was vetoed. As commish, I went off. I asked if both teams didn't include BL-quality. No one claimed that they didn't. So I asked "What's the problem?" The consensus was that they were protecting the owner from himself. I said "Fine. Should he be removed at the end of the season? If he's incapable of running his team, he doesn't need to be here." No one would step forward. The deal was re-submitted and approved.
Hamilton - we have one rule. No more cash than salary. We also have some rather inexperienced and/or unsuccessful owners. A good owner made a trade with an owner who hasn't experienced a great deal of success but he's not a slug either. The talent was pretty close but the good owner was dumping an albatross of a contract on the other guy for a couple of pretty good prospects. In MG, this goes thru and we mock the guy taking on the contract. But this isn't MG. We have 6-8 openings each season and they always seem to come from the bottom of the world. A revolving door of sorts for the bad teams. It was vetoed and I was in the forefront in explaining why it was bad for the world. You can't keep taking the future away from bad teams. It's just not good for a world.
I think the process worked in both situations.