I try not to get exasperated myself. It never fails that when I do, and then get closer to the offending driver, I see a handicapped emblem on the license plate or hanging from the mirror. That always makes me feel sheepish.
It's illegal to have anything hanging from the mirror if it hinders the full view while driving. Those things are only to be hung from the mirror when parked. My inlaws got a warning ticket from a DPS trooper and were told not to display it while the car is moving.