I've had a few spammers "try" to leave comments, but they haven't gotten past "Comments Moderation - Always" that has been in place on my blog since the beginning. It might not be convenient for those who have a lot of traffic on their blogs, but I prefer it over deleting spammers who have posted. (Settings > Comments > Comments Moderation > Always.) Plus, when I hit "publish" on an email I can immediately reply to the person who has taken the time to leave a comment. Works for me. Oh, and one more thing, on your dashboard you can, and should, check the "spam tab" on your comments and delete those ******* spammers.