Computers aren't politically correct. Computers aren't sensitive to someone's feelings. Computers don't feel social pressures or have a conscience. So when a company entrusts all of its "editorial" control to software-generated algorithms, things can go wrong.
Case in point: search "special people" on Google Images, and receive the suggested search "retards." Barry Schwartz found this anomaly through a tip and blogged about it. Fortunately for the world's largest search engine, Google employees are frequent readers of his blog, and generally fix errors he reports on within a couple hours, Schwartz said. As of this morning, the search term suggestion is no longer listed.