My worst meal backpacking was a tie amongst several of those freeze dried camp meals I tried. Generally I am an omnivore, but some of the meat versions are foul. I don't go out of my way to get the freeze dried pre-packaged meals now.

Off the trail it was some slab carne seca a guy pulled off his clothes line in the Chaco and rehydrated with some noodles. It took some fancy hand to mouth work to get the meat out and onto the floor where his dog could get it without offending the host. Poor guy was sharing his finest.