They’re there. Big guys in black suits. They stay in the audience and watch the attendees. Hubby and I had one standing right next to us at a Cheney rally once. I scared him when I took my hand out from under the sweater draped over my arm to scratch my nose. He kept his eye on me for the rest of the event.
Of course, Obama security has been lax, but I blame that on Obama, not on the SS.