It just means that they like grass. If I do not see worms in my dog's stool, then it does not have worms. Generally, worms are transmitted through microscopic eggs that cannot be seen by the human eye. Symptoms may include vomiting a worm or passing one in the stool, but these are very rare. The only way to truly tell if your dog has worms is to have the stool analyzed by a veterinarian looking for the eggs.
All dog food is the same.
The label does not always explain the quality of ingredients. In order to avoid adding supplements, pet owners should go with a premium name brand because dog food is another case where you really do get what you pay for. Dogs are color blind. Dogs can see some colors, but not as well as humans. Different types of dogs tend to see different colors.