Here's a couple of links for you to read:

http://buddypress.org/about/ - includes some use cases.
http://codex.buddypress.org/ - technical documentation.

BuddyPress is really aimed at the niche social networking market. Sports teams, newspaper sites, company and product sites, intranets. Building community around a specific topic or interest.

Why you would be getting spam from the test site I don't know, it's fairly spam free. Unless you consider email notifications of replies as spam.