Keep good company

The visibility of your site quite often can depend on its context rather than its contents. For instance, if it is a subdomain then it can depend on the other subdomains sharing the same main domain.

As a concrete example, if your site is mysite.co.cc then you probably won't have much luck getting it indexed on Google. Last week Google said they wouldn't be indexing .co.cc any more - too much spam, phishing and other dubious activity is associated with it. This will come as a shock to many .co.cc subscribers who maybe thought it was a country-level domain like .co.uk. It isn't. The country-level is just the .cc part, which belongs to the Cocos islands, and.co.cc is a privately held domain like blogger.com is. When Google de-index the entire domain, together with its many thousands of subdomains, they are just consistently applying the same rules that they would apply to any other domain that's notorious for spam and phishing, or so they say. On the other hand, it's a safe bet that if this blog gets de-indexed, it won't be because of the general level of dubious activity on other blogger.com blogs.

Another way that your site can be penalized for the faults of others is if you share an IP address with those others. With shared hosting, many sites typically share the same IP address, and if just one of them is bad then it can cause the blocking of all the others. This mainly affects the ability to get email past spam filters, but can affect search engine rank too.  That is why it can be worthwhile to pay a bit extra to have your own dedicated IP address.

Finally, linking to bad sites is a good way to have the authority of your own site dragged down. That is one reason why it doesn't always make sense to increase the inbound links to your site using mutual linking schemes (and another reason is that search engines see such schemes as attempts to artificially boost ranking rather than as genuine indicators of popularity, and adjust accordingly whenever they detect them). Not every link is a good link.

If you feel that you must reference a bad site, for instance in order to explain just how bad it is, then either use nofollow (which I'll go into in the future, for now you can look it up using your favourite search engine) or just use plain text instead of a link, which your readers can cut and paste into their browser address bar if they want to.