There's no way there getting through JFBConnect, or at least, not that we know of. Our registration flow requires that the user trying to create an account through us logged into Facebook already and has approved your application. Also, only one FB user can create an account, so unless they have mass fake FB accounts, that's not the problem.
What I would highly, highly, highly recommend, and what we use on this site, is Cedit Registration Validator (
JED link
). We use version 2 (like $20), but version 1 is free. No clue what the difference is.
Our site has at least 200 bogus registration attempts daily (we have a public forum, and are a decent size site), and Cedit catches almost all of them. It uses tools like Project Honeypot, StopForumSpam, Spamhaus, and some others to check the user's IP and email during the registration process and will block the attempt if its listed on any of those sites.
It's better than captcha or other means that can be automated. We actually removed captcha from our standard Joomla reg process about 6 months ago because it didn't do much and the plugin above closed the gap.
The only thing you'll need to look into is that the validator works with all your different registration extensions. It definitely does with Joomla. It doesn't with JFBConnect, which as mentioned above should be fine (it is on this site). I believe it works with JomSocial and not sure about AEC.
Anyways, hope that helps.. I haaaaattteee spammers, and it's a constant task staying vigil.
Alex