I don't think its bad i've done it alot of times. I don't think the smoke burns the plastic. Wouldn't the smoke taste different if the plastic was burning? It never tasted much different to me so i don't think it affects you. But i've only done it when i was desperate and had nothing else to smoke out of so only a couple times. But if your gonna smoke out of the water bottle just make sure the platic is not burning in anyway :thumbsup: