Ask News.YC: Filtering spam-filled titles?

Hello friends! In my project I'm about to launch, users will be able to submit things which have titles. These titles are instantly viewable by other people, so they will be spammed. I've heard Bayesian filtering fails when the content consists of only a few words. Is there an ideal way to filter these? How did Reddit do it? The titles aren't combined with a link, so I can't follow a link. I can filter out titles with URLs in them, though.