While I seriously doubt that overselling is really widely known, it is also quite an assumption that repeating a widely known fact has no effect on customer beh

While I seriously doubt that overselling is really widely known, it is also quite an assumption that repeating a widely known fact has no effect on customer behavior. As something between data and anecdata to support that statement, I've seen measured conversion rates indicate that customers cancel an online shopping deal after they have already agreed to it, after being redirected to PayPal. Those numbers were way too high to indicate just users who couldn't remember their passwords, so we assumed (here's the non-data part) that they jumped off when they realized that they have to log into PayPal and pay real money now. And those things are widely known, certainly so to a customer who has paid with PayPal in the past.