re: How upsetting is it to get Swai instead of catfish?

I've sold both for years. Believe or it not, in blind taste tests people actually prefer the swai or pangasius without even knowing it. One reason is that contrary to popular believe, swai generally has firmer meat and is much more straight when cooked. Visually its a much better presentation than catfish. Catfish is rarely straight or flat when cooked.

Like anything else there are quality differences in different brands of catfish. A lot depends on how they are raised/fed, processed, and stored after packing.