The number one thing that turns me off from new trackers trying to be the next big thing is that all of them try to be leet, exclusive, closed, ad infinitum, and as a result with a tiny userbase, destroy all chances of bearing any semblance to decent tracker.
There will always be bad apples no matter how you try to recruit members, be it through invites, interviews, open registration, blog recruitment, whatever. Trying to find some way of only allowing "trusted", reliable members is just a idealized goal that'll never really happen.
A larger userbase means more varied content, faster speeds, longer retention, and easier seeding. A win win in my mind.