Shelf life of herbs and spices

I pretty much use the same spices all the time so well over 3/4ths of what's in my cabinet just sits rarely being used. I wish I knew more about the shelf lifes of spices and herbs because I'd probably be able to toss out over half of what's in there. Does anyone by any chance know anything about the shelf lifes of spices and herbs? Wonder if there's a web site out there somewhere that tells us when these go bad and should be pitched.

I need some sort of a guideline so I can toss some of these spices and herbs out that have been accumulating for at least 15 years.

I do use some of the less common ones from time to time when recipes call for them and I haven't poisoned anyone here yet so my thoughts are the shelf lifes must be long. I know the herbs lose much of their potency when they're dried so I generally use fresh whenever I can. I also know dried herbs need to be sealed in air tight jars that aren't clear but what about spices? Lots of the spices I have hanging around on the shelves here are in clear jars.

Any help appreciated, I'm going through all levels of my lazy susan now and my counters look like a graveyard for spices and herbs.