Didn't stop pingback spam

Over a few months, I ended up with over two thousand comments as “ping-back.” I’m not familiar with these. I turned off ping-back for now. Perhaps this hole has been addressed but I don’t know. All I know is that I need to get a bunch of garbage out of my comments database as they act as a DOS because you need to scroll through several pages of “ping back” comments with nonsense in the text, before you could get to the page’s comment form.