How would you test something like this, if not aggregating user reports? Attempting to preemptively think of every possible thing that could be construed as politically incorrect is a Sisyphean task. It's a lot like the "H8GAYS" airline confirmation code that made headlines [1]. Delta probably blacklisted all profane words, but there are still combinations that can be perceived as offensive. Similarly, I once worked at a summer camp teens that generated users' passwords by picking two words and two numbers (all profanity was blacklisted as were 69, 88, 13, and I think a few other numbers). That didn't stop a camp attendee's parents from getting called in because their daughter was assigned the password "bloodyunhappy12" (the concern was that "bloody unhappy" referred to menstruation).

[1] http://newsfeed.time.com/2013/12/17/delta-airlines-is-very-s...