i don't see too much bad aquatic pet care at the pet store i shop at. worst is Tuesdays and Wednesday mornings. they get the new shipments of fish in Wednesday afternoon, so by then, the poor dears have been there a week. was just there last Wednesday, actually. to look at the price of gravel. saw my first ever dead betta. the other boys were understandably stressed, but their cups were clean.
now, back in the day.... when i first started betta keeping. it was pretty bad. i'd see dead fish a lot. dead goldfish, mainly. their saltwater's always been kept pretty good, though..