Auto-brewery syndrome (ABS), also called gut fermentation syndrome, is an extremely infrequent but also underrecognized disorder where ethanol is produced endogenously, similar to a typical bioreactor. The reliability of forensic alcohol analysis results is frequently challenged as the ethanol concentration in the breath, blood, and/or urine constitutes important evidence for prosecuting drivers under the influence of the alcohol. This further emphasizes the need to understand ABS, as in legal proceedings it is often presented as grounds for acquittal due to the concept that the findings could have corresponded to endogenously produced ethanol. However, this rare and underdiagnosed medical condition should not be considered as purely a lawyer’s favorite argument. Manifestations of ABS can have a severe impact on a patient’s life and pose social consequences as well. Unfortunately, barely anything has been unearthed, and aspects such as genetic susceptibility, gut-mucus-eating microorganisms, and fecal microbiome transplantation were reviewed for the first time in this context. The framework of this review was not limited to the gut microbiota exclusively; moreover, the overgrowth of microorganisms is linked to the use of antibiotics. Studies have indicated that carbohydrate fermentation occurs in locations other than in intra-intestinal flora. Accordingly, the literature was searched for cases of patients with ABS with yeast infections in their genitourinary or oral systems.