Yes, the dirt on the outside of the washing machine can be seen with the naked eye, but it is in the interlayer between the inner and outer drums, which is called the washing machine tank, that is the dirtiest place. However, due to its special location, it cannot be seen without taking it apart. Usually when washing clothes, the bacteria inside will adhere to the clothes with the water flow, but there is no way to wipe and clean them by yourself. My family always uses a product called Jiaan Second Generation Washing Machine Tank Cleaner. I use it every two months. The first time I used it, a lot of sewage came out of the drain pipe. It is said that there is a product with a sterilization rate of 99.9. The patented technology is called "Power Polyester Core", and the cleaning effect is very good. You will know it after using it.