Here's a site that shows fast food products as seen in ads along side a picture of the real thing.
I've heard there are professionals that are called in to make things look better than they are while shooting the ads or commercials... and not everything is real in the ads. No surprise to anyone, I'm sure. I always take a good look at the placement of the fingers when ads come on for small snack versions of fast food sandwiches, too. They are placed to try to make the sandwich look larger. And the bites that are taken are smaller.
Many many years ago I was in a buffet type of restaurant (can't remember the name now) and a woman was fuming because her watery bowl of liquid containing a couple of tiny tiny shrimp didn't look anything like the full bodied picture/ad on the wall. "I didn't order this! I ordered that!!" pointing to the ad. She was yelling throughout the restaurant. And I didn't blame her at all. I'm sure they didn't placate her, but I hope they gave her back her money.