Yea, the Petco near me isn't the best. The feeder fish tank is probably a 50 gallon, but divided and they all only get a third of the tank. All other tanks are murky, and over stocked. And it really is quite sickening to see the "sale" signs, like those are the fish that people don't want, so they knock them down to clearence prices. Not to mention, all the dead fish that are looming at the bottom of the tanks, and the almost dead ones hanging out in the corner of the tank, possibly infecting all the other fish in the tank with their same disease. I completely understand what you're going through.
I went in with a friend of mine, who is an utter animal lover. She's also vegetarian, and doesn't drink milk, only soy milk. I went and was looking at the Bettas (since they're my first love) and she found on buried in the back, in water that was opaque and barely clear enough to see the white, deteriorating body of what once used to be a
betta. She was absolutely discusted. As she dug him out, an employee walked by and said "Oh my, he's got some dirty water!" And my friend turned around and said, that's because the fish is dead!!! The person looked dismayed and took the cup and left us be, while my friend was completely disappointed with Petco.
In the meantime, i can't help but look at the Bettas.. Even though I already have two, and don't have enough room for another. I dunno, if i found one that stole my heart (again...) i might have to find another room, and i'd have to get another tank. I just can't help but look, y'know?