To help with this problem I've put together a new tutorial titled:
How to: Control Spam Comments & Report Spam Bloggers
Many may not realize that not only can you control the type of comments you receive on your blog, for example if they are exclusively from those with Blogger accounts or anyone including Anonymous visitors as well as having the power to actually report and offending blogger account.
So I hope this tutorial is helpful and works to assist in creating a safer and more enjoyable experience in blogland.
Enjoy!