Instruct: Classify Amazon reviews into positive or negative sentiment
Query: SERIOUS pain to clean!!

I bought these silicone reusable baking/muffin cups thinking, wow, great for the environment since I won't have to use paper baking cups anymore. They bake fine, but keep in the mind the following MAJOR con -- they are a PAIN PAIN PAIN to clean! Especially the ridges/folds where the baked food gets into. Seriously, I was wasting all kinds of water and time, using scrubber, even toothpick and toothbrush to try to get these spaces clean! And yes, of course, I greased these cups prior to baking, I used the traditional butter and flour-dusting, as well as "Pam" type cooking sprays, and STILL the resultant mess. Don't waste your money! They work in theory, but NOT in practice! I will probably use these as jello molds, since jello is easier to wash of than cake batter.