When I see one of those sign language guys in the corner of the screen, it is SO distracting I can't here a thing the speaker says. Maybe it's a distraction or a light hypnotic technique. I know that if you can heavily distract someone, the words you say afterward are less critically examined.
The pattern goes like this: 1. Give listener some confusing information 2. When the listener is confused and trying to figure out what was just said, then hit them with objectionable material.