A freeze-dried Thai Shrimp may have been my worst. I forget the brand, maybe RichMoor/Naural High. Very bad. Also, a Mountain House Beef Stroganoff which somehow hit me wrong. I ate a few bites, then decided to rely on trail snacks for dinner.
Another very bad one came from "Natural Food Backpack Dinners" in Corvallis, OR. I don't know if they're still around. I can't remember what it was called, but I seem to remember we came up with a few new names for it.

I can actually tolerate the Turkey Tetrazini.