If you see any of the kitchen spam threads then just ignore them, the accounts get deleted along with any posts or replies pretty quickly. Obviously don't click on any links in the posts, surely I don't need to say that.
There is very little that can be done to prevent these posts. They are made by real people, not bots, from constantly changing IP addresses. Just do a Google search for more details... there is a ton of information about this problem out there.
It's not just this forum that is affected, it's thousands across the internet and nobody seems to be able to do anything about it.