So it’s a very good question. My guess is most people do not want to tell the search engines, “Oh no, please you’re sending me too much traffic. Go away, I don’t want you to show me a lot more users and visitors.” So it honestly is not a request that we’ve really heard that often. I don’t know that I remember anyone ever asking for that before. So we have to prioritize in terms of engineering resources.
And even if we introduce something like a negative keyword meta tag, whenever we rolled out new indexing code or new ways of crawling things we’d have to support that going forward. So we try to think about in terms of things that we write not just creating features and features and features and features forever.
I think of that as a failure in our search quality ranking. It’s our job to make sure that, “girls in bathrooms” returns relevant results. I’m not quite sure what a relevant result would look like that would be a high quality, really useful result; it depends on the intent of the user probably. But that’s the sort of thing where we can look at that and we can say, “Okay, what do we need to do to return higher quality search results or something that’s more useful to the user?” So thank you for flagging that, but we haven’t heard enough people asking, “Please don’t send me the traffic I-I really would not like to show up for this phrase”.
If enough people requested it then we might, but it would also get into a strange situation where someone might say, “Well, you said that I was a bad restaurant and I don’t want to show up for bad restaurant.” And we really think it’s best if Google tries to rank what we think are the best search results and then we can always improve our algorithms over time, but I don’t foresee us offering a negative keyword meta tag anytime soon.
by Matt Cutts - Google's Head of Search Quality Team