There's a site called webstatsdomain that purports to be "a free online service that collects and analyzes any data about domains and keywords they are optimized for". Basically, it sucks, polluting the web with lots of broken links.
The way you as a webmaster would notice this is that on Google Webmaster Tools, your list of "Crawl Errors" is going to grow huge, making it very difficult to find legitimate 404 errors on your website. In addition, the large number of bad links might actually have a negative effect on ranking in search engines. Also, the links tend to be entirely nonsensical.
The list that Google is showing me right now is only a subset of the completely fabricated list of links that Webstatsdomain attributes to my site. Take a look at the utter nonsense that is on there:
When trying to remove a site from this database of idiocy, the service just hung for several hours, not doing anything before I gave up:
Webstatsdomain.com are a bunch of idiots who should have their internet license revoked. Simply put, don't use their service or at the very least, put no faith in it.