I'm a mostly-decent cook. In general, if my recipes don't work, it's usually because the recipe calls for too much spice. However...
1) I'm a great clipper of recipes from newspapers and magazines. This particular one came from a newspaper. It was for an Italian desert that involved some form of grain (I can't remember what it was originally; I ended up having to substitute Quinoa), dried crystalised fruit and milk. It all seemed very simple. I followed the instructions to the letter, and yet...I ended up with about three times as much filling as I should have had, and the end result was sufficiently disgusting, texture-wise, that I couldn't eat more than a mouthful. Ooops...
2) My FSIL is a great sweet baker - mostly in the line of brownies and muffins, but she also does various cakes and whatnot too. My brother has a sweet tooth. So, for Valentine's Day last year she decided to try her hand at Kendal Mint Cake...and set fire to their kitchen. I don't believe any serious damage was done (other than to the pan she'd been using) - but I do know she's never planning to try THAT again!
3) When I was a very, VERY small person, my mother was making chips (fries) in her chip pan. As chip pans are wont to do, the dingdangity thing caught fire. My father's response to this? Sling the whole flaming mass out of the back door and down the back garden...! (Perhaps the most remarkable thing about this one isn't that we didn't burn down either the house or the garden, but the fact that after this mum continued to use a chip pan up until my father died in 2009... And yes, there were a couple of other near-misses with the darn things.)
4) Then there's gone-wrong-again apple sponge - mum decided to make an apple sponge for desert one Sunday lunch. Unfortunately, for reasons that we've never been adequately able to explain, the sponge didn't cook all the way through and was, in fact, quite soggy and batter-like in the middle. Mum was upset. She was even MORE upset when my brother and I demanded she make it go wrong again next time! (One person's kitchen disaster; another person's kitchen triumph...)
5) My late father fancied himself as a cook. And while he didn't do a lot of it in later life, I can remember eating quite a wide variety of dishes on a Saturday night (his night to cook). However, one he never repeated was making Steak and Kidney Pie with stout added to the gravy. He'd had it that way in a high class London restaurant and enjoyed it and thought it would be an okay thing to try at home - and it might have been, had he not used Guinness that was well beyond its use-by date...
6) When I was in my late teens, I worked as a kitchen assistant in a nursing home. The actual chef at the nursing home...wasn't. Notoriously, on one occasion, he made cupcakes that, when dropped, bounced right back up to your hand... Anyway. For the evening meals (which is what I saw to), there was a set of four weekly menus, which we rotated through and generally, chef made whatever it was supposed to be that night and I reheated it. (Or made sandwiches and soup, if that's what the evening called for.) So we get to bubble and squeak night, very early on in my career there. It's in this big, huge tray that has to go into the oven to reheat. I get it in there, stick it on and, fifteen minutes later, as the residents are filing into the dining room, I go to pull it out and...splat. The whole contents of the tray end up on the floor. I am absolutely mortified. One of the nursing staff asks what's happened; I explain. She stares at me for a moment. I think "I'm about to get the sack". Then she says "Wait, he did WHAT?!?" Turns out, what the chef had left me to heat up as bubble and squeak wasn't, in fact, anything remotely like bubble and squeak; it shouldn't have gone in the oven...and any way, none of the residents liked the stuff! I also learned that night that I could make soup and sandwiches for forty people inside fifteen minutes...
The sequel to this occured a month later. Chef had done exactly the same thing for bubble and squeak. When I arrived, one of the nursing staff took me off to one side and said "Don't suppose you could arrange for another accident to happen to the bubble and squeak, could you?" The NEXT month, there was no bubble and squeak on the menu - the nursing staff had finally got it changed!