Not a problem.. and welcome to the site..
When you crack one of these open, how can you tell the OK from the decent to the real bad?
There are a few indicators. Smell, sight, and taste. I have had it smell good and look good and taste like death. If it comes out and is real cloudy... dump it. Usually this happens in a decanter when the decanter has mixed withthe bourbon and you are looking at dcanter material blended with bourbon. No way to seperate them Borken cork is OK, just filter. Do not drink cloudy bourbon I do not care how good it tastes..
I assume on some of the real bad the bourben tends to get a misty colour and what not.
Not always. I had an Old Fitz clear as day and I almost puked when I tasted it.
Is bourben like wine like how it will age better over time, or once out of the cask it no longer ages and will taste the same no matter how long it has been stored?
THe liquore, being distilled does not age any further, but it can oxidise and "go off" if it is contaminated.
But if the container is perfect, the juice will be just like it was when it was bottled 100 years from now.
As a side note, if you have a bourbon that has an odd smell, pour it into a glass and let it open up. SOmetimes some of the cleaning fluid or other bad smells wil burn off and it will open into a great drink... I am always concerned with I smell mildue in a distilled spirit (I hate peat by the way for scotches). It makes me think the juice had soem contamination over time... but that is me... The other rules are pretty close to what others will tell you...
Take it easy