Instruct: Classify Amazon reviews into positive or negative sentiment
Query: I should have listened to the nay-sayers here

My Hamilton Beach 05521 TrueAir Cool Mist Humidifier performed as advertised for four days, then quit working. The fan runs, the filter is in top condition - it simply will not raise the humidity. This unit replaced a Sunbeam ultrasonic humidifier that gave good service for years before quitting, but I wanted to try one that wouldn't have the "white dust" issue.I think that reviewers should be required to state HOW LONG they have used the product they are reviewing. Perhaps there would be fewer rave reviews. This Hamilton Beach humidifier appears to suffer from poor engineering or poor quality control.