The alcohol stored is more likely to go off in a plastic bottle. Glass is impermeable to O2 and CO2, hence the spirits can be stored in the glass bottles for a longer duration. Permeability factor: Plastic is not as impermeable as glass. The alcohol stored is more likely to go off in a plastic bottle.
There is a specific plastic that can be used for storing alcohol. It's called PET (polyethylene terephthalate, semicrystalline), which is compatible with holding 1-100% ethyl alcohol. This type of plastic will not get dissolved by ethanol. It is also the most common plastic that is used for food and drink storage.
Unopened liquor has an indefinite shelf life. Opened liquor lasts about a year or two before it goes bad—meaning it starts losing its color and flavor. Don't use a liquor for well drinks if you won't use the whole bottle within two years. It does not generally become toxic, though.
Even though it may seem like a good idea to clean and remove scuff marks on plastic with rubbing alcohol, it can crack and discolor acrylic and plastic. The result: A damaged item with a crack or hole that can serve as a breeding ground for bacteria.