I tried it once and felt like hell. But I think I did it wrong and went overboard too - eating bacon all the time, tuna and mayo, always worried i was getting knocked out of ketosis. I was always testing my piss w those little sticks like a chick worried she was pregnant from being a slut. Was a pain in the ass.
So you knock the diet because you didn't like it? First of all the carnivore diet isn't all about chasing ketones, and you can't eat stuff like mayo, nuts, bacon, you'll end up cheating and blowing the diet. You truthfully just need steak/beef/eggs, these foods only will provide tons of protein/fats/nutrients to your body. You won't be adding any condiments like all these sugar free things, artificial flavorings, or low sodium this and that. Just salt and pepper only. No diet coke, just water and coffee if you need it. Trust me diet is super effective and works, yes you have to get through the trial period, which can take a few weeks depending on the person, but it's well worth it.