GOOD
I guess I'm somewhat biased, since I work at one, but most of those in my area are okay, ours is better than some, worse than others. There's tons of behind the scenes work though. Hours of algae scraping, pulling deads, and water changes are all that keep ours good.
Also, about deads. I refuse to pull fish out until they are dead, not breathing heavily upside down, but no breathing at all. We pull them once every few hours, or when we get a break between customers. If it's busy they don't get pulled. Be relieved you aren't there in the morning, especially after shipment day. For all you know we just pulled them before you got there, that's why there aren't any dead ones.
And as to crickets. Getting them into bags is normally a production, they get fed to the reptiles, and every once in a while a shipping box opens up, so most Petco's have a few crickets wandering around. Call them lucky.
The main problem you find in larger chain stores is you can't keep people who know and like fish there long, because the entire idea of retail isn't very friendly toward fish. I don't even know how long I'll stay just because the selling strategy isn't always great and we insist on stocking dyed and large growing fish. I always make sure people know how large their fish can get. Haven't sold any ID Sharks yet. People still want plecos though, and balas, even after reading the labels. There are so many people who buy fish who thouroughly expect it to die, so refuse to spend any money on better choices, or listen to advice on why they are dying. Too many people forget that fish are alive.
I spend more time having to get the cheap fish for people who expect it to die than actually getting to give advice. I actually spoke to someone with a 9 inch Oscar in a 10 gallon today. He wanted to know why his son's Oscar was developing HITH. My store recommends at least a 75, and we just got 2 big Oscars dumped at our store with a 12 inch pleco in tow. None of which we really had room for.
I've been to most of the fish stores in my area, I've seen some horrible ones, and I've seen some good ones and my favorite is over a half hour away, and is currently the only place I regularly buy livestock. I pick up some at Petco, but only if they've been in a few weeks, and are very impressive fish. I buy most supplies online, since I am quite aware that Petco, even with my employee discount is almost twice as much as online for supplies.
--Mia