I think one must understand the amount of knowledge needed to work at a fish store. Do you have any idea how much stuff there is to learn about fish? There are as much fish as there are mammals, so in theory one working at this fish store must know all the factors to keeping a proper aquarium(Freshwater-Planted,Community,Semi-aggressive,aggressive, African Cichlids, specialty and more Bracking-Community, aggressive, special needs and more, Saltwater- FOWLR, REEF-SPS,LPS,Softies, Community etc. etc. etc.)and know the temperament (Of each fish?????) and the needs of the fish (every fish is unique and different and have different needs). Which is nearly impossible. Yes, granted there are common knowledge people should know but still it's very difficult to hire knowledgeable staff. Especially since fish stores can't afford to pay well (you want cheap merchandise too right?). Also most people who work at fish stores don't plan on dedicating their lives to it for the rest of their lives. They almost always move on to bigger things.
I worked at fishtown. I was in high school and there were a lot of things I didn't know and still don't know, even though I research vicariously. I'm still learning tons of things every day about fish. So how can you possibly expect knowledgeable staff? There are stores which have some people who have been in the business for a while so they know what they're talking about. Still, always expect bad information. Do your own research. I do think fish stores should hire people who are passionate and honest.