Sorry about that... The idiots seem to come in spurts. We try to get them when we see them, but it means keeping a pretty vigilant eye... Sometimes they post them faster than we can remove them..
The normal way I`ve seen on forums is monitored first post. The people which are posting the spam have no idea about what the forum is about, so will not be able to make or be bothered to make a intelligent new topic. So you will most likely get a "I`m peter I love your forum" type of post .
that was in place for a while but was causing too much frustration for new members so i think it was removed.