Blogger is consistently updating the comment and spam control function. I just read a few articles that said the new spam control function is interactive. The more you use it, the better it works. When you mark a comment as spam, Blogger acts like your email spam inbox and blocks that IP address.
If you haven't tried out the new comment tab on Blogger, please give it a try. I have mine set up to email me each time a new comment appears so I can see what is happening on my blog. This is a pretty recent advancement on Blogger. I think it started in August and there was an update in December, 2010. I had one period where I was getting 100-200 spam comments each month and had to turn on word verification. Once I started using Blogger's Comment control, I now get 2-3 a week and Blogger seems to catch them all.
I do have comment moderation turned on for any post over 31 days because for some reason, the spam bots attack my older posts. Weird, isn't it? The only reason I have it set for such a long time is that I have contests that run for a month. The spam comments are all from anonymous users. I have several readers that comment as anonymous and I don't want to block them, but you can also set up comment control to moderate ALL anonymous user.
Users with Comment Moderation turned on will continue to see comments that need moderation and have not been flagged as spam in Comments | Awaiting Moderation. Users without Comment Moderation will not see any comments in Comments | Awaiting Moderation.
Spam InboxBlogger now filters comments that are likely spam comments to a Spam Inbox, much like the spam folder in your email. When someone leaves a comment on your blog, it will be reviewed against our spam detector, and comments that are identified as possible spam will be sent to your blog’s Spam Inbox, found at Comments | Spam.
You can help improve our ability to automatically detect spam comments by checking your Spam Inbox and deleting spam comments and marking real comments that may have been flagged as spam as Not Spam.
We are always seeking feedback on how to improve this feature, so please share your feedback with us by clicking on the Report Spam Filtering Issues.
If you have questions about what constitutes spam on Blogger, please review our Content Policies.