10 year old is OK if originally not crap.
If you are unsure, you can condition them by slowly charging them up to the rated voltage with a current-limiting series resistor (like 10k or something), but I wouldn't bother for 10-year old stuff.
If you are actually making products and sell them, then I would be careful if you go much beyond that 10 years...
Electrolytic caps are widely used in almost every product, and the products don't just go bad in ten years. Most work fine for 50 years or so, with some exceptions, but they are more exceptions than a rule.