What are these spam sites doing?

[doclove]

I was looking through my logs this morning and found that there were around 5 sites that were listed as my top referrers for the day. These were sites that were unrelated to my site's content so I checked them out. All 5 were spam sites relating to diet pill or gambling. On the pages that are referring to me there is no mention of my site or link. Checking the logs further, I see that the pages that are being linked to are random and some don't even exist anymore but are still listed in Google. Checking the IP addresses of the people coming from that site show that most of them are coming from China or Russia. I also ran some tools to see if they were doing a redirect to my site, but it doesn't appear that they are.

This all points to something fishy going on but I can't figure out what they are doing. I don't want to lose any search engine rankings, adsense revenue, or end up being hacked. Anyone have any ideas on further research I can do to find out what they might be up to? Anyone else have this happen to them?

More Information:
I just looked at the server logs for my other sites and it appears that all of my sites have this problem and that it is more like 50-100 spam sites rather than the original 5 that are doing this to me.

[The Contractor]

[google.com...]

[Dijkgraaf]

They are running bots that are Referrer Spamming.

Make sure your logs or summaries stats aren't publicly accessible, if these can't be spidered they don't gain any benefit from it.

There is not a lot you can do about it although you could try blocking them via .htaccess, but probably not worth the effort unless they are causing actual problems.