If they don't understand the concept of it, dogs are still able to associate humans with security and food. And I guess shooting paintballs can be considered as teaching, although it sounds brutal.

We still know very little about how brains work, and determining how intelligent an animal is can be a bit difficult.

And keep in mind, these results can vary wildly in the same group. A common example is crows and ravens. I think studies have even concluded that they are actually semi conscious, although we dont know to which extent. Some unfortunate people have even found themselves harassed by groups of them for years after hurting one of them.

Dont fuck with them, I guess.

You may be underestimating the intelligence of animals :P

If they wont learn about it, they will for sure connect seeing humans and pain.