At my walmart on display are some pretty healthy bettas, their cup is twice as big as petsmarts and it looks like they get daily water changes. But if you turn around and look on a shelf theres all of the sick bettas piled up in the corner. Its as though they get a shipment, do daily water changes but once sick, they are hidden, but until then they are displayed in clean cups. My fishy came from there, on display in his clean cup and hasnt had a single issue so changing the water daily on the healthy ones i LOVE and its possible to buy a healthy betta if i choose from the ones on display, but ignoring the sick ones hidden in the shadows is really hard to do.
RIP to my little Coraline.