There are several reasons for ineffective TASER deployments. The most common reason is lack of a circuit, which is required for a TASER to do its job. This is not TASER failure, but simply the product of any given scenario. If you miss with one or both probes - no circuit. If a wire breaks during a fall or struggle - no circuit. If a probe is pulled loose during a fall or struggle - no circuit. If your target is wearing loose clothes - no circuit. If your target is wearing thick clothes - no circuit. If your target is overweight - insufficient muscle groups are affected. If you're too close to your target - insufficient probe spread. If your battery is dead - no power. If you used improper batteries - insufficient power (older models). [LINK]
Mr. 'Tactical' was attempting to explain how tasers are a viable self-protection option, and then proceeded to score an own-goal by helpfully listing just a few of the many reasons why tasers are not a reliable option.