When beef jerky has gone bad you can usually tell by looking at the beef jerky.
The beef jerky when it has gone bad will usually have mold on the beef jerky or the color of the beef jerky may have changed.
If you notice any discoloration or mold on the beef jerky then it should be thrown out especially if the beef jerky has mold on it.
The beef jerky when bad may also smell bad or have a bad taste to it when you bite into it.
If the beef jerky tastes bad or has a bad smell to the beef jerky then throw it out to avoid getting sick.
If you eat bad beef jerky then you will usually get a stomach ache, possible vomiting and sometimes diarrhea.
It usually will not make you deathly sick but it's not worth risking your health so if in doubt about the beef jerky being good or not then throw it out if it's older.