I don't use the plugin, but I frequently visit blogs that do. I have never spammed the comments of any of these blogs - in fact, I believe that I've only ever left one comment on a blog before, and it wasn't an endorsement or advertisement of any kind. Today, though, I woke up to find that my IP address has apparently been 'flagged'. There is no option offered that allows me to contest this or to contact somebody, and I really have to say that I'm impressed with how incredibly unprofessional it is not only to mistakenly flag me for no reason, but to force me to create a wordpress account and track down this forum simply to tell anybody. A+ job blocking me from some of my favorite websites, guys. I really appreciate your efforts.
http://wordpress.org/plugins/avh-first-defense-against-spam/