Walgreens recently installed screens on their coolers that run ads when a user is not interacting with it. While cool in theory, there are quite a few user experience issues that arise.
This was Fuzzy Math's first article of the "Scary UX in the Wild" series. We examined the Chicago's transportation application, Ventra, and all the associated UX issues that arise when interacting with it.
To avoid "scary" UX situations, it is important to take into account usability, but that is only one aspect of what contributes to a good user experience.