Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Gross!

I loved the mug at first because it kept my coffee hot for quite a while. Then I realized that despite my cleaning efforts there was a build up around the inside of the mouthpiece. You can't get at it to clean it and the top does not come apart for cleaning. I tried using q-tips, toothpicks, rolled up papertowels, etc. Nothing can get at it. I even bought a bottle brush to try to salvage the mug but that was too big as well. I will not drink from a moldy, nasty cup so I have to throw them out. What a waste! Check out the pics Amazon has posted to show you what you'll find inside the top....disgusting! Don't buy this mug!