Spices really aren't the kind of thing to go bad. I think BensMom is right, they can lose flavor a little, but not much.

I use some spices that I've had around for years. They taste fine to me. If I was a connoisseur then I could have a different opinion, but my oregano from 3 years ago tastes fine in my spaghetti today. Spices like cloves, and cinnamon stick might taste good after decades since they have such stong flavors. Keep the herbs and spices sealed and in a dark place like a cabinet and I think they keep quite well.

I didn't know there were other "rules" on spices till I saw this thread :o

We go though spices rather quickly here.. so ours are gone usually in 6 months. My gram has spices though that she has had for quite a long time.. and her food is still wonderful as ever.