I use one litre milk bottles for my ice so my cooler doesn't get all wet & gross inside. I have tried repeatedly to clean them, but I just cannot get the milk smell out of them.
I don't drink much milk when I'm camping, just a little when cooking, so when I travel, I fill a 500mL (pint, I guess?) Nalgene bottle with milk (so it doesn't leak in the cooler) and now it has a faint milk smell no matter how many times I clean it.
Any ideas?