Sometimes you will notice a nut that is discolored or looks visibly rotten but, sadly, a lot of the time, it is the taste test that is the first alert. haha
Walnuts can look moldy and pistachios can look dark brown and crumbly, but almonds not so much. I just read that chipped or cracked almonds allow for the oils to oxidize and go rancid faster which accounts for the nasty taste. Storing them in the freezer can help combat the oxidizing rate. The article also said to avoid eating the wrinkly ones too for the same reason.

Thanks

Not that I have discerned, Usually it is trial and error. If I spit it out it was probably bad tasting.