In short no, the worse that could happen is that you get frustrated another website has stolen your work and repurposed it as their own. I currently have atleast 50 scraper websites with my content on them, be it abstracts of my blog posts or complete rip offs, however none of them have affected my rankings on Google (I don’t really care about Yahoo or MSN Live to tell the truth).
I must admit that its frustrating to see spammy scraper sites pop outta no where with a carbon copy of my blog but repurposed with their name on it, not to mention completely untargetted Adsense ads all over the place. I mean the least you guys could do is to atleast put some effort in blending the ads in with the rest of the content. Only takes a few hours and I am sure your CTR will go through the roof.
Some scraper sites takes abstracts of my blog posts to republish but are good enough to have a link back to my post. Its all good, until I realise that they use a completely random name as the author for the post. For example, http://pagerankpimp.com/2008/02/21/website-delisted-from-google-wonder-why-hmm/ took an abstract of my post, places links back to it but says that the person who wrote the post is some fictitious character named “Dennis Kubes”. I mean seriously, atleast give me some credit man, come on, my name is Francis Lee ok, get your facts right.
As for if these scraper sites affect your rankings, there is really nothing to worry about, chances are that their pages would never be shown on SERPs due to duplicate content. Google has a pretty good idea who the original owner of a specific piece of article is and if you ping services such as FeedBurner, they would keep a record of when the post was created. Note that Feedburner is owned by Google so they would have a good idea who owns the post.
Ofcourse, the scraper / spam website could still appear on Google SERPs if someone searches for something weird like “Dennis kubes” where Google can’t find any information on except for that specific website.
As to what you would do to these guys, my advice would be to just leave them alone. You don’t really get anything out of abusing them or spamming their comments section, plus, there are too many to deal with. They will get what they deserve in the long run from the Big G anyways. “What goes around, comes around” as sang by Justin Timberlake.
Chill out, Relax, take a Kit-Kat and just plain ignore them.