I bought a bunch of nuts like walnuts, pecans, and almonds from Costco. Unfortunately it was more than I could consume in a short period of time, and I'm now worried they might be going bad. How can I tell without just eating them and hoping I don't die on the toilet?
If I eat nuts I always buy them in the shell and crack them just before I eat them. I really think that it is not a good idea to buy large quantities of shelled nuts, even if they are stored in the freezer. When were they shelled? It could have been months before you bought them.
Nuts in the shell remain fresher for longer and because they are so hard to get into and it can take a while to eat only a handful, I eat less of them. This means I do not binge on them (I love nuts!).
I would keep un-shelled nuts for about a few weeks maximum (remembering they have probably travelled for weeks before I bought them) before thinking twice about eating them, that's just a personal thing and of course, go with your taste buds and sight; it is much easier to tell if any are off just by the look of a nut straight out of the shell.
If you can get local nuts in the autumn they will be guaranteed to be fresher. Then you will have more knowledge about their palatability.