Why can't there be someone else's old pot?

Because what others use is definitely unsanitary, and the disease is from the mouth. If you eat with these things, it will have a great impact on your health.

Moreover, after the old pot has been used for many years, rust and this oil residue are mixed together to form black deposited scale. It is very harmful to human body.

Rust is iron oxide, which is harmful to human liver after long-term use. In addition, the oil residue that has been deposited for many years is mixed together and gathered at the side of the pot. If it is not handled well, it is highly carcinogenic to the human body.