I am certainly no expert, I would think that they are just fine. I took some bottles that my parents had in their bar in the 70s with me to college less than 10 years ago (so they were at least 20 years old too) and drank from them, no problem. In fact, I STILL have a couple of those bottles in my bar now! As long as it was just liquor in the bottle (no fruit juice mixture, something that would spoil) it should be fine. Pour yourself a dram and see, if you don't turn green, then you're good to go!
