Is PetSmart a good place to buy fish?

I bought 2 bettas 4 days ago (not at once) and within 2 days of each other, they died (the first one i bought was in a cup, the second one was in a tank). I'm planning to get some goldfish at PetSmart but I'm kind of worried since the bettas died that the goldfish will be infected, too, and a few days ago I saw a dead goldfish in one of the tanks. They also squished like 50 goldfish into one of their tanks (I have no idea how many gallons).