This was before I knew about Scrapebox but I knew about spam and all that stuff and my whitehat high ranking site was getting hit with spam comments (this was prior to askimet). I used to go through each comment and approve the non-website linked ones. But there was one that I did approve. It was something along these lines: "Hello webmaster can I use some of the information from this post if I provide a link back to your site?" I approved it with the backlink and the owner got a whopping high PR backlink amidst all the spam. People that don't know about scrapebox will approve this comment and there's a pretty good chance of it happening. Good luck and remember to spin.