I'm going to apply for a job this week, when I get all my information together (of past employers and such).
I think that not all petstores of the same chain are bad, and not all are good. I think it all depends on where you are and what kind of people they hire. If you get a store that has hired lazy people, things just don't go right. If they are more careful of who they hire, I think that makes the store better.
The man I talked to at the Petco seemed to know fish pretty well, and all the tanks were spotless. Overcrowded (a little over half the tanks were overcrowded), but spotless.