"The sales tactics on that page are also used by people trying to scam you"

Who are these alleged people, where have you met them, how do you know they're scammers, and more importantly, have you ever met one doing this alleged scamming with programming books?

"Offering a full refund is something scammers do. Then they give you your money back. Run away!"

If you are so afraid of being scammed that you think a refund offer makes something suspicious, it's probably a good time to evaluate your buying habits…