Comments on blog postings are, without a doubt, the number one place spammers look to drop links. Links are used to promote the page rank of other websites. Google sees how many times other pages “link” to your page and your page rank climbs up slowly but surely. These comments are often spammy in nature and irrelevant to the blog posting. Instead of avoiding the comment links by using the NoFollow tag on your blog, why not set the rules out in the open and tell your spammers to give a little if they want to take a little.
The key to generating free traffic from your spammers is quite an easy one. In a blog post, or a sticky on the side of your blog, explain that you will be allowing comments with links to be posted to your blog. Then, add some rules to the process. Tell the spammers out right that the comment will have to be relevant and that a link to your site would be appreciated elsewhere in their commenting travels.
Your blog may not get a flood of traffic from the commenter’s links, but it will get a few commenters here and there that like the fact that you are honest about your commenting practices and that you are allowing them to complete the task of comment linking with little or no stress. Rest assured, you will still have to moderate the comments and pluck out the ones that are blatantly overdone, but all in all, you may find the comments attracted to your blog of higher quality.
Another important rule to set is the use of anchor text. Links in a comment look messy and unprofessional. If the commenter does not know how to link anchor text using a bit of html, the link and the comment does not need to be on your blog.
I think the do follow is important. People love to give links and that is just fine and dandy. How else do you get links? And also why are people so stingy?