It's important to use this sparingly. When grepping is obviously broken, the adversary will adapt, most likely by writing a script to rewrite the Unicode, then

It's important to use this sparingly. When grepping is obviously broken, the adversary will adapt, most likely by writing a script to rewrite the Unicode, then it's back to business as usual. On the other hand, if grep has a 95% success rate, the adversary may well never notice, and build his or her mental model of the program on flawed understanding. That's when the real fun begins.