Sam's hires a higher caliber person than most stores. If you don't have the I.Q., then just work at Walmart.
They give a character quiz and you must pass it. You also need to be available to work ANY hours to get the second interview. You can change it later, so don't worry if that scares you.
The biggest thing to know about Sam's is that you are being hired to hard sell their Plus Memberships, Credit Cards, and warranties. They don't give a rat's backside if they sell anything on the shelves, but you'd better sell the extra stuff or they'll fire you.