Instruct: Classify a review as either positive or negative.
Query: Leaky, leaky, leaky

I bought these bottles because of their great popularity. However, no matter how dry each part was, they constantly leaked. The nipples never look clean, they get very filmy looking, even after boiling or putting them in the dishwasher. My daughter had a lot of problems with gas and these bottles contributed to that. I switched to the Dr. Brown bottles, and she slept better, and did not have these painful gas problems. The bottles also cleaned better than the Avent.