A few candidates:
1) 20 years ago, camping with a group by a lake and making instant oatmeal in the morning, still not sure why, but when we put unfiltered, untreated lake water in to the pot with the oatmeal the whole thing turned dark blue (like in chemistry class in school when using an indicators for acid/base on something that's a base) None of us were willing to risk trying to eat it. (still do wonder what was in that water!)
2) 15 years ago, Before I learned that lighter is better, when I still carried 50-60 lbs for a weekend trip, one trip a friend of mine got us American military rations... we had 3 completely different meals according to the labelling on the packages, but we couldn't tell them apart by colour, texture, or flavour... they were awful!
3) 10 years ago, A friend of mine offered to cook supper, he said he'd bring steak and potatoes, sounded good to me! ... well he brought steak and potatoes, but no marinade, no spices, no salt or pepper, no butter, no flavour of any kind, he then proceeded to burn the steaks...
I can't say that my current meals are particularly adventurous, or even amazingly good, but I can always eat them with a smile, so they can't be that bad (though I have to admit, that is one of the areas that I know I can lighten my load, and part of the reason for my joining this forum, to get some good ideas for lightweight food (without sacrificing too much flavour))