Whether trained or not, most dogs will understand short verbal commands. However, they don’t understand angry yelling, and such behavior can make them sad, scared, or upset. Dogs cannot make a connection about their bad behavior the same way humans do and don’t have memories of things they did. For instance, if you come from work and yell at your dog for tearing up your couch, they will not understand why. So, yelling is ineffective. Plus, it can confuse and sadden your dog.