I've turned the blacklist back on. I turned it off yesterday and have had a couple of spam comments get through. The blacklist itself doesn't always catch the spam comments but it does give me a one click method of removing them. With it turned off I lose the easy removal.
If your comment is refused you should get a message telling you why; the reason is logged, but, unfortunately the full comment txt isn't. The best approach if you have a legitimate comment that you cant post is to either email me, or leave a simple comment that explains that you cant comment ;) (I know...) Anyway, if you do that then I can remove the offending, over zealous, blacklist entry and post your comment for you...