Do you know the TV advert for the Nationwide? It features an overweight bank manager from an imaginary competitor who teases, lies and suggests that his rate of interest is like a piece of bait to reel in the customer. His picture is in the window of Nationwide branches.
It's annoying because it breaks the first rule of visual aids. Don't put up a picture of something you want to say is wrong. You end up reinforcing the negative image.
Your visual aids should add emphasis to the 5% of your presentation you want people to remember without fail.
Nationwide. They have fat managers who put fish-hooks through their customers' lips, don't they? Or did I remember it wrong?