The other day while traversing through my blog referral links, I noticed a search query coming from a site that had DoFollow in the domain name. Upon closer inspection, I discovered that the site was a DoFollow search engine that allegedly indexes thousands of blog posts from 400 or more blogs.
I still feel as if having the DoFollow attribute enabled is another magnet for comment spam. However, if you feel the need to only comment on blogs that pass along a few drops of Google Juice, this search engine might be of help to you. Let me know if you perform a search of your blog or blog posts and come up with any results.
Although in the past, I have stated that I use DoFollow on my own personal blog. However, I have since changed my mind and have disabled the DoFollow plugin.