We have a coffee shop downtown, and often people sit at the outdoor tables with their dogs. Thee were three of us outside with our dogs one day. Coby was very good, although at that time a jumpy (but quiet) puppy.
There was a couple with two large dogs that were being trained with attentiveness using treats each time a dog walked by. Each time a dog or person would walk by, they stood up and got their dogs attention using treats and kept the attention until the passer-by was gone.
And the third table had a an elderly lady and her beautiful big dog. She had a squirt bottle right on her table and when dogs and people would pass and the dog would begin to bark, she would use the squirt bottle and speak gently to her dog.
So I think everyone tries things until they find what works. If I saw you in Petsmart with a squirt bottle, I would be proud of you for trying something to control the behavior (I feel that way about parents who try to make their kids behave too.
) .... but if you squirt in the store, be sure to wipe up any spray - you wouldn't want someone to slip in a "puddle" .... which reminds me of my REAL pet peeve with people not cleaning up after their dogs in the pet store. LOL