Wal-Mart exists to make money and they will, and their salespeople have little motivation to do much other than peddle their wares.
once i was at walmart and watched the guy sell a pleco to some lady who was telling him how her other one had died. i asked her what size tank she had (5gal) and told her that they can get to 20 inches. she just looked at me. i was like, ''well, it's going to get too big for that pretty soon''. she just replied, ''yeah, well, if it lives that long''. i went back and talked to the guy, and told him how she had a 5 gal tank, and we had a little discussion. he actually knew quite a bit about fish, but "management" had made it clear that he wasn't allowed to express his opinions. the lady wanted it for algae control, and i told him that if she could cut down on her lights and feed less, it would go away. he was like, "yeah, exactly! that's just what i used to tell people, but i got yelled at for it".
after that, knowing how employees aren't allowed to say anything, i have no problem starting up conversations with people about the fish they're buying. if the workers know anything about fish, it probably drives them crazy to know that they can't give out any advice that isn't in their little handbook. if someone changes their mind and doesn't buy the fish, that's no money out of the employee's pocket, you know? and unless they're under orders to immediately silence any customers who try to interfere, they won't get in trouble for it.