I think this is all a bit over-considered.
I will admit that rFactor was crap in this regard because you had no idea what was good or bad. Having a poor rating system for mods, and not knowing the expectations that those rating cars had led to that issue.
Ie, some people are happy that a car looks correct and that is ok, others consider sounds important too, then physics, etc etc...
So why not just have a trusted reliable team that rate cars on key aspects. They can then provide a specific rating to that content.
Ie, 10/9/10 for gfx/sound/physics.
Authors can then work to improve things if they don't get high enough ratings to end up on a top-list which can just appear on a sticky on this forum perhaps.
Self-moderation is important I think. Relying on AC team to moderate us would be a waste of their time in making sure content was any good.
It sounds harsh, but if you want to quell bad or questionable content, or just content that doesn't do AC full justice, then you need to rate it appropriately.
Indeed, you can just choose to only rate content on your seal of approval thread that you deem good enough for a seal of approval.
You don't have to go saying someone's mod is crap, provide them with reasons why it didn't get the seal of approval, how they can get it to a standard where it would.
Ie, be positive and constructive even if content isn't good enough, so it's never seen as disheartening or putting people down.
As for content mis-matches, well I guess that is just something that AC needs to consider when programming. It shouldn't be hard for the server/client code to do a checksum on folder contents or something to check specific contents are the same or not... hmmmm...
Ie, check models, check models and textures, check everything, check nothing, for different levels of strictness.
Hmmm, probably similar code to just checking that people are not cheating (ie, editing track grip values on their local track files or something)
Dave