Sorry, there's no way to check. If you're interested in that cabal or want more information, you can try going to said cabal and finding someone that is not a leader in that cabal. If you can't find anyone inside of the cabal, you can try again later or ask around about certain people or if they know anyone that is in a certain cabal. If all else fails the lyceum has some information about various cabals plus the help files (but I'm certain you've looked at those).

If you find you're really interested in a cabal and you've decided to join, you can write a note stating you'd like to join. Then RP this out just as if you were allready a member of said cabal. Sure, you don't have their nice cabal powers, but you can act like you are an active member. If you still can't find a cabal leader, the probably is high that an immortal of the cabal can bump you up.

Good luck!