I got a microfiber cloth and some baking soda in a wide mouthed shallow cup. I wet the cloth and sprinked some bs on it and started scrubbing. the stains started coming off like magic and ten minutes later, my cup looked like new! I turned it inside out and cleaned that too. I also used a small toothbrush and bs to clean the words and crevices. The only places I couldn't get clean were the holes, and the inside of the stem. But it is so much better!
After this ritual, I put my cup with some water in a never-used mug in the microwave for five minutes. When it was done boiling, I put in a bag of herbal tea to convince my mom that I was "just making tea". I'm not sure if this was a bad idea, but I let it soak in the honey ginsing mint tea until the water was cooler and then took it out. It smells really nice now and I rinsed it off afterwards. What do you guys think?