Found this automated blog from a google blog alert and if this type of affiliate site becomes popular with spammers it could ruin the authority that blogs have acquired. I am seeing more and more of them.

http://cialist.blogspot.com/2008/07/coca-heart-women-chosen.html

Why resort to blog comment spam when you can create unlimited blogs and interlink to your heart's desire? And make money from adsense while you are at it!

I think Google's algo is smart enough to pick up the spammy content and not rank the blogs well - but since they choose to list the pages in their index the links would still have value.

I don't think blogs have any special "authority" that can be ruined. Blogs are really treated no differently than any web page. It is just that blogs usually have new content on a regular basis. Google will spider frequently any web page where the content is often changed as they consider such sites to be NEWS sites - and they want to be able to be on top of the news.

Once the "news" is old it fades to the back pages whether it is a regular web page or a blog.

Google would know that the spam blogs are not "news" and they would eventually treat them just like any other spam website.

I use WordPress and it has a very nice spam detection, so far not a single spam went through. Blogging software are becoming smarter at it.