the fish you'll find and how they're treated usually varies by the store.
My local Petcos take pretty good care of their bettas. They put them in slightly larger cups, keep their water clean, rarely see a dead one, and they have a pretty good selection. I've seen VT, CT, Delta, HM, PK, King PKs and Giant HMPKs there.
My local Petsmart does the blue water thing and doesn't clean the water as often. When i try to pick up a cup they are stuck to the "placemats" they place them on on the shelves. so I'll stick to Petco for my bettas in the future.