Chinese hotels have a way to track the cleaning history of bed linen. PHOTO: PRAKASH MATHEMA / AFPHave you ever wondered if the sheets in your hotel room were actually changed after the last guest left? A Chinese city is trying to put the question to bed using tracking devices. Reports about dirty hotel bed sheets have prompted online uproar in the past. In 2017, hotel reviewers in China secretly left fluorescence stamps on hotel items and found that several luxury hotels in Beijing failed to change bed sheets.