Each CC is different, so there ain't no "single place" to look for information. The common denominators of such community are interaction and leadership.
My two Pfennig: Look for the owners and directors of a CC, see what they state on their profiles and get in contact with them via their walls.
If they are active, you will get an impression of them and their CC to make an informed decision, and become invited if you are lucky.
If they are not, you may consider the CC dead wood and walk away.