I think spammers can easily take advantage of this site because of the lack of "mark as spam" feature.
Please read the FAQ. An excerpt:
What if I see bad things happening?
Please use our flagging system to let us know about it. Each comment has a small flag icon, and every post has a flag menu at the bottom. Take advantage of it! We actively moderate our community, but we need your help to do so. Anything that is getting consistently flagged by our community members will be investigated and followed up on. And of course you can always email us directly if you feel the matter is extremely urgent.