In the modern day world, search engines are beginning to play an increasingly important role in our lives as they often determine what we get around to seeing, but more importantly, what we don't get to see.
Eli Pariser discusses this issue in the TED Talk video below:
This issue was also highlighted by Bruce Tognazzini in an article from July 2010:
Fundamentally, the issue of "personalised results" is problematic. While the option of being able to have junk-content-aggregators (you know, those annoying el-cheapo copycats that just do a full copy of Wikipedia content, or an aggregation of Wikipedia + 3 dictionaries that used to plague all the serious searches I would try to do in the past) is nice to have (and perhaps still a valid type of personalisation, should we want it), it is things like hiding certain categories of content which is perhaps more problematic.
Taken to the extreme, this may mean that we never get to see that article or resource which highlights exactly the root cause of some infuriating bug you've been battling for the past 3-6 hours, simply on the basis that you never paid attention to those types of things in the past. Instead, all your searches are met with "low-hanging junk", or stuff that you already know, and which is of no use to what you're trying to figure out since you're looking for that next level of insight.
Would this also meant that perhaps one day (and perhaps not too far into the future), an experienced researcher may have greater access to interesting stuff than someone starting out (or vice versa)?