Remember, kids, always wipe your devices of all personal data before trading them in or returning them to a retailer. Some Best Buy customers are learning this the hard way after the consumer electronics retail chain failed to reset returned devices before reselling them as open box items.

The most recent incident happened in Mission Viejo, California where a man named Michael Urban bought an open box Apple TV, only to find the device was still logged in to multiple services including Hulu, Netflix, iTunes, and HBO Now.

While Urban did the right thing by restoring the device to its manufacturer settings, he condemned Best Buy's security practices: "Although one could say the original owner should have known better and reset the unit before returning it, many/most people are probably clueless in this area. So if the retailer accepts the return and resells the item, it's their responsibility to return it to factory defaults."

Best Buy told Ars Technica that its many locations wipe "thousands of devices and return them to factory settings" every year. In situations where this doesn't happen, Best Buy says it conflicts with the values of the company and how it expects to approach customer data.

A similar incident took place last month in which Ars Technica contributor John Ferguson reportedly purchased a computer from Best Buy and was still able to log in to the previous owner's account.

"It was in the box the entire time," Ferguson wrote. "Not only did they sell me a computer with someone else's data still on it, they gave me the password as well. No hacking required." The password was included with the computer on a piece of paper that the previous owner had written their password on.

And there are several more stories like that. A Best Buy customer forum reveals that, in June of this year, a similar incident was reported. The user claimed to have bought an open box 13-inch Retina Macbook Pro and ensured that the fine print promised a like-new device restored to its factory settings.

It was a gift for her sister, but when upon receiving the product, it was overheating from being powered on inside the box. When the notebook was opened, she was prompted to log in to the account belonging to a person named "Steve H". No one had made sure the computer had been refreshed before making the sale. No one had checked to see if it could be accessed.

Following an apology, an employee then proceeded to tell the customer that it would take an entire five days to fix the problem. He was eventually able to convince the Best Buy to replace it with a new one.

But perhaps not all stories have the same happy ending; leaving your data open to strangers could lead to more unfortunate consequences. Our advice stands: always remember to wipe your devices before trading them in – especially so, if you're trading in at Best Buy, it seems.