When attempting to create an account on Samsung.com, users are given four checkboxes to select. One of these checkboxes is optional. However, when the fifth checkbox labelled "I have read and agree to all the above" is selected, it also automatically selects an optional checkbox for "News and special offers." This design pattern may lead users to sign up for promotional emails unknowingly.
Samsung decides to opt users into an optional service without giving them a choice to do so. This is an example of a "dark pattern" known as "Privacy Zuckering," in which a company uses deception to gather more user information. In this case, the optional service is the receipt of promotional emails sent to the user's email address.
A more user-friendly approach would be to leave the optional service unchecked by default and give users a choice to opt-in rather than tricking them into opting in. This way, users have full control over the services they choose to receive.
Found by Arvid Kahl