With taking pictures you have to be careful in some of those stores. They usually wont allow pictures to be taken. There has been threads like this before and employees from petco and petsmart said the stores arent usually camera friendly. So just do it discretely.

My petsmart is actually pretty good. They dont have the most knowledgeable staff. Ive had to help people before in the store with the employee right there.. That being said the staff does a good job of taking care of the animals.