People who don't eat donuts with the chocolate facing down. It tastes much better.
Don't see why anyone should care how others enjoy their food, as long as it's not repulsive to the surroundings.
And while I've never tried doughnuts (does spelling of doughnut count as a pet peeve?) with the chocolate facing down, it reminds me of an experiment we did as kids. We dipped a cotton swab in different flavors (sugar water, dissolved coffee, salt water, etc) and touched different areas on the tongue. It's pretty amazing to discover that receptacles for different flavors are located at different areas of your mouth.