Petsmart DOES train its workers on dog training procedures but each store varies on how good of a trainer it actually has. My friend near our place is an excellent trainer and i even used to ask her for training tips when i couldn't quite figure out how to do certain things myself. on the other hand the 2 trainer in that same location isn't as helpful and rushes through classes which is hard for most people working with their dogs. If you plan on trying a different location you can ask the trainer if you can sit in the first class andregister after if you think it'll work for you.
I think using the petsmart training mostly as socialization is a good idea until you find a better trainer that suits your needs
Use youtube how to videos as a supplement. There are some excellent trainers that tape how to videos there!