If you've ever seen those "Click To Reveal Price" or "Price Only Revealed At Checkout" products online, this here is one reason why. They help businesses keep discounted prices hidden from Amazon's crawlers.

This can also be true if the manufacturer of the product requires that retailers not offer a price below a certain amount. This is called the minimum advertised price (MAP) and is common for big brands like Apple. Another way to get around the minimum advertised price is to bundle the product with some other product or service, such as is done with cell phone contracts.

Blame the manufacturer for this, not the reseller.

Is it effective, like, at all?