Good powder smells of acetone and bad powder has a strong acid reek to it. Bad powder also usually shows a red or orange dust. If it smells all right and looks all right, shoot it.
Age don't matter much to powder. Heat does. If it has been allowed to get too hot, it goes bad rapidly. Stored properly, powder can last a very long time.
I'm still shooting Hodgon from cardboard boxes, and Alcan from the '60s myself.