It depends a lot on how the bottle was stored , some degradation is to be expected . If it still has it's Autumn Formula smell then it can at least serve as a cover scent though it may no longer be effective in the odor elimination department . It's composition should also be considered , if it's a baking soda-peroxide mix , which a lot of the commercial ones are ,it's probably gone flat . Adding a small amount of peroxide and baking soda should revive it , don't forget to leave the cap loose at first until it settles down. A scent eliminator with an L-Serine neutralizer may still be good , but there's only one way to find out ...