The phrase, "I wouldn't feed that to my dog" is not used exclusively by dog owners. It is simply a reference to a low standard of food.
Ah, one of my many humiliating misunderstandings. It always feels like such a blessing to be part of the human race when making a mistaking an idiom for a truth is the cause for hysterical laughter and teasing /sarcasm/. I am not stupid. I think logically. Yes, that means that sometimes I misinterpret your meaning when you use an obscure phrase or idiom. No, that does not mean that you can mock me. I get that it can be slightly amusing and you might not be able to help laughing a little, but please just let it go. Believe it or not, I too have feelings and they are hurt when you laugh at me. It's humiliating enough as it is.