Matt Cutts: Just to go back in time and give a little context on this we used to have in our Webmaster guidelines something like, “It is impossible for a competitor to hurt you.” And Then if you look at the history of, for example, Sex.com people would even send in a fax and pretend to be the domain owner and get the domain from someone else and then use it for their own nefarious purposes.
So it’s possible for competitors to pretend to be competitors so we went ahead and removed the language that is impossible for a competitor to hurt another competitor and we replaced it with language along the lines of it’s very hard or we try very hard to make sure that a competitor can’t hurt another competitor.
That’s still the case. Whenever we write and algorithm, for example that looks at incoming links we do think about, “What if a competitor tried to hurt someone else” and we try to put in code so that is not easy to do, that it’s not the case the someone can easily hurt someone else.
As a result we haven’t really felt the need to add a feature into web master console or webmaster tools to say, “Hey here is my site and I have a bunch of links coming in from a porn site or that competitor made of low quality.” We haven’t really provided a way to say, “I don’t trust these links.”
It’s something that in theory we could do, maybe we’ll do down the road. I do hear the request every so often from time to time so we’ll take that into account but at least for the time being we don’t offer that as a feature.