cheap consumer electronics can be assembled in a method with screws intended to be used once into a plastic cylindrical receiving part (injection molded usually). The screws have a certain sort of spiral to them that you don't see with screws intended to be repeatedly installed and removed. On the cheapest stuff, removing the screw once and then reinstalling it can result in the clamshell assembly of the upper and lower injection molded parts becoming permanently loose... One example would be a "modern" humidifier such as you can buy at Target that is never intended to be repaired or disassembled.