I haven't shopped petco in many years... I've found them to be as above... unhealthy animals, poor selection of cheap, over priced merchandise... until very recently.
A brand new Petco opened recently in Springfield, MO. Guy they hired to run the fish section is a long time member of the local reef club. Knows his stuff, and has made an effort to stock useful dry goods, and so far, is keeping clean, healthy tanks... and at reasonable prices, even. I was in there a few weeks back, bought some frozen mysis and formula one cubes, at a reasonable price. Tanks looked great. A friend called me from the store last week, says they've got a gorgeous 3" powder brown tang in stock, fat and healthy looking, $39. I'm not really wanting a powder brown, but you gotta admit, that's not a bad price.
Seems to be all about who's running the store. And... that seems to be predicated on what they're willing to pay someone to run the store... which isn't usually very much.