Can we drink this old alcohol?

We got a ton of old alcohol from a friend of my husband's that was kept in a liquor cabinet. Some of it is opened and some not. The age is unknown, but I would say 5-15 years old maybe? Anyways, some of it has pale colored floater things in the alcohol, which I'm sure is yeast particles, but I need to know if that means it is unsafe to consume. So do the yeast particles mean it is too old? Should it be thrown out? BTW, it is all hard liquor.