If the plant looks dry don’t buy it.

When plants dry out, to the point of wilting, natural defence mechanisms will have been activated. The plants will go into survival mode. Normally the flowers will die or drop off, the young flower buds will fail to open and often drop off as the plat tries to conserve moisture. 
Pack bedding and plants in small pots are often the first to dry out

The plant will try to save its self by sacrificing some leaves If you look some will have changed colour or even dropped off. What you can’t see is the damage to the roots, these will have started to die back.

At this point, you might feel sorry for them and be tempted to save them. They may look like they could come round with some watering but save your money the roots are damaged and will start to die.

Some stores have started to use big plastic trays filled with water to stand plants in, this would be a good idea for aquatic or bog plants but standing in water will kill most plants. The roots become starved of air and quickly die.