The past two potlucks at my work have been AWESOME. Everybody brings excellent food, and we make sure to have vegetraian options too. The key to potluck is to have a sign up ahead of time.
I don't eat everybody's food so I look for the containers I know came from the store or I don't eat it. I am usually hungry after work potlucks.
There was a woman at my current job who told some of her coworkers thta she lets let dogs lick her dishes before she put them in the dishwasher. She was hurt when no one ate her dish.