Do they ever go out of date? I just found a few that had disappeared for a few years. I guess it can't hurt to try anyways..
If the cartridges have butane in them, they should be good. I would say that if the pads have been sealed and the package is still intact, they should still be okay. I bought a huge box of them several years ago, and I am still using them, and they work, at least they keep the bugs away. V
I haven't bought pads or butane in 3 years and mine still work. As long as there is fluid in the cartridge, you're good.