Webmasters and Internet marketing professionals have long worried about the possibility of rankings being negatively affected by some inbound links. A search for "inbound links hurt" at Google will yield thousands of results that show the conflicting views on this subject. Google itself, as well as primary and secondary research by many SEO practitioners, however, has suggested that some inbound links can hurt search engine rankings. This has often led to the question: "Can my competitors hurt my rankings by maliciously linking to my site from 'bad neighborhoods' or by using sitewide and FFA link submission tactics?"
A recent thread at WebMasterWorld Forums discusses this topic. The original poster points to the Google guidelines that admit that the possibility of inbound links hurting rankings exists. He then asks how this could be used by a competitor. Some good discussion follows, mostly along the lines of other arguments on this topic. However, one somewhat new twist on the topic is raised when a member suggest that linking to non-www versions of a website that does not have canonical issues can sometimes cause duplicate content problems.
Senior member "g1smd" explains eloquently, beginning with the following:
If a site is fully indexed as www and all links inside the site always point to www, and all non-www requests are 301 redirected to www, then you can't get any of it indexed at non-www, ever. It is bomb proof to that particular effect.He mentions "bomb proof" in reference to the long-utilized practice known as "Google bombing."
The idea of Google-bombing has proven to be valid, especially during searches for terms like "moron" around Presidential election times in the US. So if someone was to combine the practices of linking from bad neighborhoods and using non-www versions of a competitor's web pages, could they effectively harm them in the rankings?