Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Doesn't work!!!

Horrible product. My dogs did not even bark and the collar would spray. They didn't even make a noise and it went off. My dogs were terrified of the collars and when we tried them again after tightening the collars, they were shaking and cowering. And they still sprayed for no reason! And on top of THAT, we couldn't return them b/c they have the citronella which is considered hazardous??!! Seriously? What a waste of money. ZERO stars.