Here are some options to help deal with spam:
Manually approve all new posts or new users
You can make it so that posts have to be approved before they are public (approve post count), or so that users have to be approved (must approve users)
/admin/site_settings/category/all_results?filter=Approve
Akismet
Do you have the Akismet plugin installed? Setting this up can help with spam.
Watched Words
You could also make so that posts with certain words will be automatically blocked, flagged or require approval, in Watched Words
/admin/customize/watched_words
