I've almost always had a dog throughout my entire life. I've had dogs that ate most foods when offered and then others who vacuumed up non food items like they were living garbage disposals.
My current dog was a rescue from a shelter that closed down right before the COVID lockdown. He had a really rough life and had spent most of it living in the shelter after being abandoned in the woods.
He's my little cPTSD buddy and I love him with all of my heart, but my god this dog is the pickiest eater I've ever seen. He's not feeling well these days, (which definitely doesn't help), but to a certain extent he's always been this way since I brought him home.
When he first came to live with us, I asked what kind of food we should get him. They said he was used to just eating the cheapest kibble, so it didn't matter. We still had some of the fairly pricey dog food leftover that we had been feeding our previous dog. She had loved it, so we figured it would be fine.
Almost the entire first week he lived with us, he just wouldn't eat anything except table scraps.
We switched to a different kibble and that worked for a while, but eventually he just stopped eating until we switched to something else. Even wet dog food is hard to get him to eat if it's been in the rotation for too long.
Not only does he just flat out refuse most dog food after a certain point, if he finds we're trying to sneak medicine in human food he likes, even once, he will refuse to ever eat it again.
I'm trying to get him to gain some weight. So far he has eaten for a while and then gotten sick of: chicken, hamburger, bacon, and most recently rice cooked in bacon fat (we're a pescatarian house, so keep in mind this is all being cooked exclusively for him)..
The rice in bacon fat seemed like a big hit until I made the mistake of mixing in a teaspoon of pumpkin (which he also liked at one point) into it.
As of now the only thing he will eat seems to be grilled shrimp. :(
