I was naive enough to rely on the advice of a PetSmart employee when I bought my first tank for my daycare class. I bought two balloon mollies to start with, and when I asked what my cheapest tank option was, the girl sold me a 5 gallon BOWL. I realize now that much more research was required on my part, but I was totally clueless and figured PetSmart would steer me in the right direction. Luckily I jumped on the internet as soon as I got the fish home and straightened myself out, but incompetent teenage employees and amateur fish owners do not make a good combination, and PetSmart ought to know that.
One time I went with my mom when she took her water to be tested, and the guy started freaking out, going, "Your pH is way high. C'mere, let me show you some products." When I asked him how high it was, and he kept going, "It's way high. You really need to bring it down a lot." So I asked him for a specific number, and he dances around it for a minute before saying, "It's like almost at 7.5. You must have some coral or something in there, 'cause that's really high." Funny how her 2 dwarf gouramis hadn't seemed to object...[/sarcasm]
So he tries to sell her a pH decreaser, a pH stabilizer, and a liquid master test kit. If she'd gone without me, she'd have ended up spending at least $50 on totally unnecessary (and some potentially harmful) products. I don't know if the guy thought he was helping or if he was just trying to rip my mom off, but let's just say we keep to the privately owned shops now.