Review on The Unemployed Philosophers Guild Heat Reactive Constellation Mug - Reveal 11 Constellations with Coffee or Tea - Presented in a Playful Gift Box by Richard Dean

The mug changes color because it has a color changing sticker. The sticker is not waterproof. The mug cannot be washed in the dishwasher. Even with normal hand washing, if the mug is not immersed in water for a long time, the edges will start to become rough. It takes a while for a cup to heat up and change, and when it changes, it does so quickly. Basically you end up watching the paint dry and when it finally dries there's a "blink and you miss" situation. The mug does change color as advertised, but the effect isn't as impressive and the decal makes the mug more uncomfortable than it should be. A real mug has a standard design and is nothing special.