How many years are opened bottles of alcoholic beverages good

I dont' believe it's years, I think it's actually months. Opened liquor loses a little bit of its taste the longer it sits in a fridge (this I know from college). I hope this help answers your question.

This is a scary question!  Alcohol goes "bad" much in the same way fruit does...so, like the poster before me said, it's more a matter of weeks or months than years.  If the alcohol has added or natural sugar in it, forget about it...

And if you're considering drinking it anyways, you might need help :)

http://www.newmethodwellness.com/holistic-vs-traditional.html

Wine left open to the air turns to vinegar in less than a month.  Some microbes aid the process, but just having oxygen on the wine will do it too.

That is why most quality wine is packed under nitrogen.  Once you open the bottle, drink it in a few days.