If he's barking at dogs there's a really good chance it's anxiety and taking him to Petsmart probably won't help. My dogs (even Sam who doesn't have anxiety) don't like it there. You'd be much better off outside, where you have more control and can walk away. Sometimes people at petsmart just assume your dog is friendly and come right over even if you ask for some space. We have tons of dogs in our neighborhood so when I work with Loki I just sit in the front lawn and wait for dogs to walk by. Everyone walks their dog when they get home at 5pm.
The treat method works better for anxiety/reactive barking. The spray bottle really only works if the dog is barking to get attention. If they are already on edge spraying them isn't going to help.
