Instruct: Classify a given Amazon review as either positive or negative.
Query: Lid cannot be cleaned

The lids simply cannot be cleaned. If you buy these I suggest you clean them with a water pick daily. I have two of these. Been using them a long time. Tried everything I could think of to clean the lid. Finally used a water pick on it. You should see the gunk that came out of it. And even after doing that last night my wife tells me she had a big piece of gunk in her coffee this morning. I must have loosened it but not flushed it out. Great thermal properties but we're throwing them away.