Dear Johnny,
Well, if something is going to be released as part of CentOS (contrib repo or not), then it is going to be correct and it is going to be vetted by someone that I PERSONALLY trust ... or it is going to be personally tested by me prior to release. Otherwise, it is not going to be released.
Then you should not perhaps not call it 'Contrib' repository if noone that you do not personally know can add content to it.
The Fedora project has published very good guidelines which explain how to build high quality packages:
https://fedoraproject.org/wiki/Packaging/Guidelines
As mentioned before, spec files or SRPMs can be reviewed locally (using lint) and via bugtracker.
Mentorship could help new packagers to build 'standard conform' packages.
Rebuild could happen automatically in koji.
If you meet those requirements (I know you, know your work, and personally trust you with my servers), then you can get on a team to do things ... if you don't, you can't.
In my pov the requirements that have to be met to become a developer could be lined out very clearly. Membership applications could then be discussed within a board.
Until I get kicked out of CentOS (I don't think that is happening any time soon), that will be one of the standards that we use.
Which means you are the king, feeding the folk?
Not very 'Community' orientated, sorry.
Best Regards Marcus