who, moi?

I caught a climpse of this sign at the Pomona courthouse (or the Los Angeles County Courthouse Eastern division or whatever).

I'm bemused at the exhortation to "beware" of "rip-off artists". You would think that if someone were so skilled at ripping people off that his or her craft had asceneded to the level of art that maybe detection would not be as simple as this red arial directive would suggest.