I use Scent Killer, I firmly believe that it works well enough to fool a deer's nose-I've had MANY instances that I could have reached out and touched deer from my natural ground blinds-I hollow out brush piles or use rose vines as natural webbing-one this year I was sitting in, had my feet propped up on the wall of my blind and kicked back to sleep, had "Code Blue" doe estrus on my soles-a six point buck walked up and started licking my boots!!! I had a doe come up to within 4ft of my blind-she stopped, but her two fawns came closer, one nibbled on the leaves on the wall, and one walked RIGHT ON IN!!!! It was really wide open on one side-dang thing walked around the wall and right inside!

Anyway---does it go bad, yes and no, a white creamy (like wet baking soda) settles out, so you'll spray just a little bit then it'll clog up, sprays pretty much just water then ruins your aspirator-shake it up before spraying it after it's sat for a while and it's fine.

Some Cover scents-not scent eliminators-that I've used do spoil, I do recall one smelling a lot like vinegar once-but since I started using this Scent Killer and Code Blue, I'm not planning on going back to that stuff!