Yes, there're some spam filters, and the OpenKM team also we clean data ( at least weekly ). We had downgrade some spam rules because we observed problems to the standard users when registering or adding posts in the forums. Is quite difficult to balance between strong security rules and the issues that cause to the standard users.
That happens because seems our forum has a good internet score and spammers trying to take advantage of it. Only for your information in past, we had been attacked with more than 1000 post in a day ... we success controlling this kind attacks ( usually robots ), but seems currently the spammers are human because some of the posts in the forum are really finest in terms of contents.