Would it be safe to drink these bottles of old liquor?

Hello, I'm hoping someone here can help me. I've been searching the Internet and can't find a good consistent answer.

I recently came in the possession of some really old bottles of liquor. They were my Grandfathers who died back in the mid-80's. I'm just not sure how safe or dangerous they are. I'm more curious than anything, but I wouldn't mind tasting them to see if I would like them or not as they are not brands that I have ever seen. A couple are German (he was German).

Here is what I have:

• Ezra Brooks Kentucky Straight Bourbon Whisky 4 years old - Previously opened, corked bottle
• Mouquin Brandy 10 years old - Previously opened, corked bottle
• Walker's DeLuxe Bourbon Aged 8 Years - Previously opened, corked bottle (looks slightly cloudy)
• Bouchet Naturmild Weinbrand - Previously opened, screw top bottle
• Chronik Kaiserbirn Likor - Previously opened, screw top bottle

Any help would be appreciated!

[BourbonDrinker]

If the liquid is clear at room temperature, the cork is in good shape, and it's unopened, I'd drink it. After a good sniff test, and a quick sip test.
I wouldn't drink 20 year old previously opened whisky. If out was extraordinary rare or prized, others probably would.

[James]

If clear and tastes ok I would drink it I have not gotten sick yet.