A great way to test your spices would be to shake the bottle with a lid on, remove the lid and then smell them. If there is no scent then your spices have lost their "spice." Spices will also lose some of their colour as they lose their flavour.
Way to keep them fresh:
- place lid on jar directly after use
- try not to buy too large of containers if you don't use the spice as often
- when using try to sprinkle away from the heat
- store in a cool, dry, dark place