I'm wondering what town / city this PetCo is in, want to make sure I never shop there.
We have a local Pet co that keeps the tanks clean and will ask questions and try to steer people into making the correct choices, but will give in if pushed.
the pet co in leominster ma, has the best selection of saltwater/freshwater I've ever seen in one of their store, tanks are always clean, fish look healthy and they are like the enquirer about your set up to see if you are able to care for the fish you want to buy. I've also hear them refused to sell and the manager back up the salesperson.
The pet smart in the same town, over heard a older lady and her husband wanting to buy 2 common pleco, 2 oscars and a few assorted dwarf cichlids for a 30 gallon set up. Saleperson talked them into 2 bristle nosed pleco, no oscars and then sold them a couple dwarf cichlids which would have been okay had the lady not mentioned as she was leaving that her son had been there the day before and had been sold 3 pacus for the same set up.The poor sales girl looked like she was about to cry when she heard that. I did try and tell them about the pacus but Lady sweetly told me her SON knew how to keep them small and not to worry they would be fine.