I have a discussion forum on my personal site. As it was for learning purposes, I had just started 2 threads, one dealing with facebook usage and one dealing with a question about letters vs emails. I was flooded with spam replies for both the threads, but more on the facebook question. So, I deleted that thread. But I continued to get spam on the second thread.

I now have a captcha which I learnt to use with the help of my sitepoint friends. One needs to type in the letters in the captcha to be able to see my discussion forum. But now I have a strange problem. I do not see any spam messages on my site, but when I go to my cpanel and the phpmyadmin section, I can see many spam messages in my reply table. I just keep truncating the table. It becomes impossible to delete only the spam replies and retain the genuine replies as there are so many spam replies. Why is this happening? How is it not visible on the webpage?