My mother still has the same cream of tartar she got when she got married back in 1956. You couldn't pay me to eat anything she produces with meringue
I think she still has the same ground mustard, too.
Dried herbs and spices have a definite shelf life. I usually change mine with the seasons. All sorts of variables can effect their taste and quality. Humidity, heat, cold...all these conditions have an effect. Unfortunately, herbs and spices are expensive and it's hard to toss something out.
Buy small and use it often. That way, you never have much to toss. You will notice a difference if your herbs and spices are always fresh.