I was at petsmart and witnessed a sales person sell 4 3-4 inch comet goldfish to a couple buying a 10 gallon tank. I had recently just learned comets need a huge tank or a pond. I said something to the employee getting my 5 endlers guppies and he wasn't too concerned. I've only been to petsmart once for fish.
When I go to petco- my normal LFS
, I make it a point to tell them when I see dead or sick fish in their tanks. They do a very good job keeping their tanks clean and healthy looking. On my last visit a tank of gold gourami's had the beginnings of ich. So I told the guy. I've talked to about every employee there that works in aquatics and I've learned who to ask advice from and who not to.