Hey just have a quick question, Does have spam comments on your blog damage the traffic to your blog? It is just weird, ever since i installed akismet and filtered through the comments and removed any spam, my traffic has increased.
They could have an effect in regards to how your blog is perceived by readers. If you let spam comments through and reader sees a bunch of worthless gibberish and links to Viagra sites in your comments, it makes your site look pretty trashy and would probably discourage real readers from leaving comments.
Search engines detect those words like Viagra and what not. Your rankings may have increased when they realized you weren't promoting such things.