Those who want to conceal the content of their communications can do so by replacing words that might trigger attention by other words or locutions that seem more ordinary. We address the problem of discovering such substitutions when the original and substitute words have the same natural frequency. We construct a number of measures, all of which search for local discontinuities in properties such as string and bag-of-words frequency. Each of these measures individually is a weak detector. However, we show that combining them produces a detector that is reasonably effective.