Traveling in Kunming and staying in a hotel, I came in and saw a strange woman's underwear with menstrual blood falling on the toilet. How to complain and solve it?

Take evidence first, take videos or photos, and contact the Consumers Association directly to ask. Then ask their manager to negotiate a solution. There must be a third party present, otherwise they will clean up the scene, and you are basically hopeless. The store is lying, my friend. You are traveling in Kunming, and Kunming certainly has no backrest.

But in other words, people are in rivers and lakes. If you put up with it at first, you may be glad later. That's it, right?