For training I use small chopped pieces of cheese, liver treats and cooked sausage from Coles. I vary them, and the doggies love them.
However, for reeaally stressful situations such as the vet or the dog mobile blower, the only thing that works for my dog is doggy chocs from Coles.
These are carob chocs, about the size of a choc melt. They are perfectly safe, and my dogs go completely gaga, but they are very fattening, so they are kept as my secret weapon for highly stressful situations where nothing else will work.
My girl is really terrified of the blower that the mobile dog washer uses, but as she is a golden retriever, she needs to be dried off. So I use the dog chocs to distract her while the dog groomer uses the blower. These treats are the only thing that will distract her sufficiently to stand relatively still for the groomer.
I initially tried other treats and she ignores them, being too stressed to be interested in food. It wasn't until I found these that we could keep her calm enough for the blower.