Yeah, my dog (pit bull) is fairly picky. He generally will not eat dry food unless it is mixed with wet food or meat. He will not eat lamb. He only eats a couple of veggies (carrots, and sometimes cabbage.) He will not eat raw meat (well, he did when he was younger – once he ate two pounds of raw meat I had left unattended for a few minutes while getting some stuff ready to stuff it into sausage, but now he won’t touch it.) He’ll eat grass, but I’ve never seen him eat poop or anything else non-foodlike. He does love any type of sweets, though.
Our cats did, too. We gave it to them for hairballs and they loved their “kitty butter.”
I give my Siamese a bit of vaseline on their toes ( they will lick every bit of it off ) for hairball prevention. It really pisses them off. They won’t talk to me, til treat time when I do it. They are ‘oh so snooty’ kitty-cats.
Pugs have no sense of danger when it comes to food. Ours eats leaves, wood, rocks…anything that’s on the floor, or where he can otherwise reach it, is fair game.
Leads to trouble sometimes. Our previous pug (and I want to stress up front that she came through fine with no ill effects) ran right up to some weeds and ate them after we’d sprayed them with herbicide, which we discovered to have arsenic in it. Dumb pug.
My Boston Terrier loves seafood (Naturally! She’s from Boston*). The Shih Tzu doesn’t, but she loves fruit, which the Terrier won’t touch.
Point being, not every dog eats every thing.
The other way you can tell is when she speaks, she says “Bahk, Bahk”*
** I’ve been milking this joke for 10 years.
What brand of relish is that? I could use it on my cooking mistakes. 
We have a generic striped cat who started taking dumps on the floor. Turns out she’s feeding her dog.
Also, a dog’s least developed sense is taste. I imagine this is at least partially evolutionary, as a scavenger has to eat what it finds.
Sent from my HTC U11 using Tapatalk
As I understand it, a major reason is that dogs are good at vomiting. If they eat something they can’t handle they just throw it up and walk away. As opposed to for example horses who basically can’t vomit, and are screwed if they swallow something dangerous.